Troubleshooting / SINAMICS V20 faults

Siemens SINAMICS V20 Fault Codes

The fault (F) and alarm (A) codes of the Siemens SINAMICS V20 inverter: what each one means, how the inverter reacts, the likely causes, the first checks with the parameters to look at, and how to log it so it stops coming back.

How faults and alarms show

On the built-in BOP, a fault shows the fault icon (a cross in a circle) and the display jumps to the faults screen, which shows the fault number with an F in front, for example F11. An alarm shows the alarm icon and its number with an A in front, for example A501. With several messages active, the BOP shows all faults first, one after another, then all alarms.

Press UP or DOWN to step through the active faults. Hold OK for more than 2 seconds to see the converter status at the moment of the fault (setpoint r0954, output voltage r0958, output current r0957, DC link voltage r0956, converter status r0955), and press OK briefly to go back.

If a fault stays active with no key press for 60 seconds, the faults screen returns and the backlight flashes. To acknowledge a fault, fix the cause and press OK, or use an external acknowledge: digital input 3 is set to fault acknowledge by default (P0703 = 9, source P2103, second source P2104).

Pressing M only ignores the fault for now; the fault icon stays until the fault is acknowledged. Some faults (for example F51, F64 and F350) clear only after a power cycle. Alarms cannot be acknowledged; they clear by themselves once the cause is gone.

The fault history is r0947 (fault codes of the latest trips), with r0948 (fault time), r0949 (fault value) and P0952 (number of trips stored; set to 0 to clear). r2110 shows 2 active and 2 past warnings.

Safety first.
Siemens warns that the power component capacitors keep a hazardous voltage for up to 5 minutes after the power supply is switched off, and touching live parts can cause death or serious injury. Wait 5 minutes, then check that the unit really is voltage free before you start work.

If a braking resistor is fitted, disconnect the supply and wait at least five minutes for the capacitors to discharge before working on it, and remember that braking resistors get hot in operation (sources 1, 2). Follow lockout/tagout and your site's safe-work procedures, and check the manual for your exact model before you act.

Quick lookup

Faults stop the inverter and the machine it drives, so in OEE they are availability losses; alarms let it keep running until you act.

Type a code or a word (overcurrent, overvoltage, overtemperature, PID) to filter the list. Click a code for its causes and first checks.

55 codes

CodeTypeName
F1FaultOvercurrent
F2FaultOvervoltage
F3FaultUndervoltage
F4FaultConverter overtemperature
F5FaultConverter I2t
F6FaultChip temperature rise exceeds critical levels
F11FaultMotor overtemperature
F20FaultDC ripple too high
F60FaultAsic timeout
F51FaultParameter EEPROM fault
F85FaultExternal fault
F221FaultPID feedback below minimum value
F222FaultPID feedback above maximum value
F80FaultSignal lost on analog input
F72FaultUSS/MODBUS setpoint fault (on RS485)
F71FaultUSS setpoint fault (on RS232)
F35FaultMaximum number of auto restart attempts exceeded
F41FaultMotor data identification failure
F23FaultOutput current ripple too high
F12FaultConverter temperature signal lost
F52FaultConverter software fault
F395FaultAcceptance test/confirmation pending
F61FaultSD card parameter cloning failed
F62FaultParameter cloning contents invalid
F63FaultParameter cloning contents incompatible
F64FaultConverter attempted to do an automatic clone during startup
F70FaultI/O Extension Module communication fault
F26FaultInternal error
F100FaultWatchdog reset
F101FaultStack overflow
F200FaultScript error
F350FaultConfiguration vector for the converter failed
F410FaultCavitation protection failure
F452FaultLoad monitoring trip
A501AlarmCurrent limit
A502AlarmOvervoltage limit
A503AlarmUndervoltage limit
A505AlarmConverter I2t
A511AlarmMotor overtemperature I2t
A504AlarmConverter overtemperature
A506AlarmIGBT junction temperature rise warning
A507AlarmConverter temperature signal lost
A910AlarmVdc_max controller de-activated
A911AlarmVdc_max controller active
A912AlarmVdc_min controller active
A922AlarmNo load applied to converter
A930AlarmCavitation protection warn
A936AlarmPID autotuning active
A535AlarmBraking resistor overload
A541AlarmMotor data identification active
A952AlarmLoad monitoring warning
A523AlarmOutput current ripple too high
A921AlarmAnalog output parameters not set properly
A923AlarmBoth JOG left and JOG right are requested
A600AlarmRTOS overrun warning

Each code: causes and first checks

F1: Overcurrent

Hits OEE: Availability

What it means: The converter measured output current above its limit and tripped to protect the power stage.[1][2]

Drive response: OFF2 (pulses off, motor coasts to a stop); fixed default

Likely causes

  • Motor power (P0307) does not match the converter power (r0206)
  • Short circuit in the motor leads
  • Earth (ground) fault in the motor or motor cable
  • Ramp-up too fast or starting boost too high
  • Motor blocked or overloaded, or motor data and stator resistance (P0350) wrong

First checks, in this order

  1. Read the fault value r0949: 0 or 22 means the hardware tripped, 1 means software reported it.
  2. Confirm that motor power P0307 matches converter power r0206.
  3. Check the motor cable and motor for short circuits and earth faults, and keep the cable length within the limits.
  4. Check that the motor data match the motor in use, including stator resistance P0350.
  5. Make sure the motor is not blocked or overloaded.
  6. Increase the ramp-up time P1120 and reduce the starting boost P1312.

F2: Overvoltage

Hits OEE: Availability

What it means: The DC link voltage went too high, usually because the motor fed energy back into the converter.[1][2]

Drive response: OFF2 (pulses off, motor coasts to a stop); fixed default

Likely causes

  • Supply voltage too high
  • Regenerative mode: ramp-down too fast for the load inertia, or an active load driving the motor
  • Vdc controller disabled or set wrong (P1240)
  • Braking power needed is above the specified limits

First checks, in this order

  1. Read r0949: 0 means hardware reported, 1 or 2 means software reported.
  2. Check that the supply voltage setting P0210 and the real supply are within the rating plate limits.
  3. Lengthen the ramp-down time P1121 to suit the load inertia.
  4. Check that the Vdc controller is enabled in P1240 (factory default 1, Vdc_max controller). Set P1240 = 0 only when a braking resistor is fitted.
  5. For high inertia or a load that drives the motor, fit a braking resistor.

F3: Undervoltage

Hits OEE: Availability

What it means: The DC link voltage dropped too low, usually from a supply dip or supply loss.[1][2]

Drive response: OFF2 (pulses off, motor coasts to a stop); fixed default

Likely causes

  • Main supply failed or dipped
  • Shock load outside the specified limits

First checks, in this order

  1. Read r0949: 0 means hardware reported, 1 or 2 means software reported.
  2. Measure the supply voltage at the converter input terminals.
  3. Check the load for heavy shock loads.
  4. For short supply dips, kinetic buffering (P1240 = 2 or 3, Vdc_min controller) helps the converter ride through.
  5. Automatic restart settings P1210 = 8 to 11 handle F3 after mains brownouts or blackouts.

F4: Converter overtemperature

Hits OEE: Availability

What it means: The converter heat sink or IGBT temperature reached the trip limit.[1][2]

Drive response: OFF2 (pulses off, motor coasts to a stop); fixed default

Likely causes

  • Converter overloaded
  • Ventilation inadequate
  • Pulse frequency too high
  • Surrounding temperature too high
  • Fan not working

First checks, in this order

  1. Check the load and the load cycle.
  2. Confirm that motor power P0307 matches converter power r0206.
  3. Set the pulse frequency back to its default value.
  4. Check the surrounding temperature and the air flow around the converter.
  5. Check that the fan turns while the converter runs.
  6. Read r0037[0] (heat sink temperature) and r0037[1] (chip junction temperature).
  7. Check P0290 (converter overload reaction): the default 2 reduces pulse frequency, output current and frequency before a trip, while 1 trips with no reduction.

F5: Converter I2t

Hits OEE: Availability

What it means: The converter overload (I2t) model reached 100%: the converter ran above its rated current for too long.[1][2]

Drive response: OFF2 (pulses off, motor coasts to a stop); fixed default

Likely causes

  • Converter overloaded
  • Load cycle too demanding
  • Motor power (P0307) larger than the converter power (r0206)

First checks, in this order

  1. Check that the load cycle is within the specified limits.
  2. Confirm that motor power P0307 matches converter power r0206.
  3. Watch r0036 (converter overload utilization). F5 can only be cleared once r0036 is below the I2t warning level P0294 (default 95%), so let the converter recover first.
  4. Alarm A505 warns before F5 trips.

F6: Chip temperature rise exceeds critical levels

Hits OEE: Availability

What it means: The IGBT chip (junction) temperature, or its rise above the heat sink temperature, passed the critical level, typically on a hard start or a sudden load step.[1][2]

Drive response: OFF2 (pulses off, motor coasts to a stop); fixed default

Likely causes

  • Load at start-up too high
  • Load step too high
  • Ramp-up too fast

First checks, in this order

  1. Check the load and the size of load steps.
  2. Increase the ramp-up time P1120.
  3. Confirm that motor power P0307 matches converter power r0206.
  4. Use P0290 = 0 or 2 to prevent F6: the converter then reduces its output instead of tripping. Settings 1 and 3 allow an F6 trip.

F11: Motor overtemperature

Hits OEE: Availability

What it means: The motor thermal model calculates that the motor is too hot. The trip level is 10% above the motor temperature warning threshold P0604.[1][2]

Drive response: OFF2 (pulses off, motor coasts to a stop) by default; can be changed with P2100/P2101

Likely causes

  • Motor overloaded, or load steps too high
  • Motor overtemperature values (P0626 to P0628) or warning threshold (P0604) set wrong
  • Small motor running below 15 Hz: the model can trip even though the real motor temperature is within limits

First checks, in this order

  1. Check the load and the load steps.
  2. Check the motor overtemperature values P0626 to P0628 and the warning threshold P0604.
  3. Compare the motor current with the rating plate current and check the real motor temperature.
  4. If both are within limits on a small motor below 15 Hz, set P0335 = 1 as Siemens advises.
  5. P0610 sets the reaction at the warning threshold (factory default 6: warning and trip F11). Alarm A511 shows first.

F20: DC ripple too high

Hits OEE: Availability

What it means: The calculated ripple on the DC link voltage passed the safe threshold, most often because one mains input phase is missing.[1][2]

Drive response: OFF2 (pulses off, motor coasts to a stop) by default; can be changed with P2100/P2101

Likely causes

  • Loss of one mains input phase, for example a blown fuse or a loose supply terminal
  • Faulty supply wiring

First checks, in this order

  1. Check the mains supply wiring and terminals.
  2. Check the input fuses or breaker on every phase.
  3. Measure the voltage on all three input phases, ideally while the converter runs under load.

F60: Asic timeout

Hits OEE: Availability

What it means: Internal communication inside the converter failed.[1][2]

Drive response: OFF2 (pulses off, motor coasts to a stop); fixed default

Likely causes

  • Electrical noise (EMC problems) when the fault appears now and then
  • Converter hardware fault when the fault appears as soon as mains is applied and an ON command is given

First checks, in this order

  1. Read r0949: 0 means a hardware-reported link failure, 1 a software-reported one.
  2. If the fault is sporadic, check and improve EMC (shielded motor cable, good grounding, power and control cables kept apart) and use an EMC filter.
  3. If the fault appears right after mains is applied and ON is given, contact Siemens service or replace the converter.

F51: Parameter EEPROM fault

Hits OEE: Availability

What it means: Reading or writing the parameter memory (EEPROM) failed, or the memory is full because too many parameters were changed.[1][2]

Drive response: OFF2 (pulses off, motor coasts to a stop); fixed default

Likely causes

  • EEPROM read or write failure
  • EEPROM full (r0949 = 1)
  • Factory reset interrupted by a restart or power failure (r0949 = 9000 + block number)

First checks, in this order

  1. Power cycle the converter, since some parameters may not have been read correctly.
  2. If the fault stays, do a factory reset (P0970 = 31) and set the parameters again.
  3. If the EEPROM is full, set some parameters back to their defaults and power cycle.
  4. Note the r0949 value (block and read or write action). If nothing helps, replace the converter.

F85: External fault

Hits OEE: Availability

What it means: An external fault was triggered through the external fault command (control word 2, bit 13), for example from a digital input set to external trip.[1][2]

Drive response: OFF2 (pulses off, motor coasts to a stop) by default; can be changed with P2100/P2101

Likely causes

  • External device signalled a fault through the source selected in P2106
  • Digital input set to external trip (function 29) is active, or its wiring is open

First checks, in this order

  1. Check the external device and its wiring to the converter input.
  2. Check P2106 (source of external fault) and which digital input has function 29 in P0701 to P0704.
  3. If the external fault function is not needed, disable control word 2 bit 13 as the command source or disable the terminal input for the fault trigger.

F221: PID feedback below minimum value

Hits OEE: Availability

What it means: With the PID controller enabled (P2200 = 1), the PID feedback signal fell below the minimum value set in P2268.[1][2]

Drive response: OFF2 (pulses off, motor coasts to a stop) by default; can be changed with P2100/P2101

Likely causes

  • Feedback sensor signal lost or too low, for example a broken wire or failed transmitter
  • P2268 set too high
  • Feedback gain P2269 set wrong

First checks, in this order

  1. Check the feedback sensor and its wiring to the analog input.
  2. Change P2268 (minimum value for PID feedback, default 0.00%).
  3. Adjust the feedback gain P2269.

F222: PID feedback above maximum value

Hits OEE: Availability

What it means: With the PID controller enabled (P2200 = 1), the PID feedback signal rose above the maximum value set in P2267.[1][2]

Drive response: OFF2 (pulses off, motor coasts to a stop) by default; can be changed with P2100/P2101

Likely causes

  • Feedback sensor signal too high or faulty
  • P2267 set too low
  • Feedback gain P2269 set wrong

First checks, in this order

  1. Check the feedback sensor, its range and its wiring.
  2. Change P2267 (maximum value for PID feedback, default 100.00%).
  3. Adjust the feedback gain P2269.

F80: Signal lost on analog input

Hits OEE: Availability

What it means: An analog input with monitoring enabled lost its signal or went outside its limits.[1][2]

Drive response: OFF2 (pulses off, motor coasts to a stop); fixed default

Likely causes

  • Broken wire
  • Signal out of limits

First checks, in this order

  1. Check the analog input wiring and the signal source.
  2. Check that the analog inputs stay within their voltage and current limits.
  3. Check P0756: settings 1 (0 to 10 V) and 3 (0 to 20 mA) enable monitoring. With a deadband set in P0761, F80 trips when the input falls below 50% of the deadband voltage.
  4. If the wiring and signal are good, contact Siemens service or replace the converter.

F72: USS/MODBUS setpoint fault (on RS485)

Hits OEE: Availability

What it means: No setpoint telegram arrived from the USS or Modbus master on RS485 within the telegram off time.[1][2]

Drive response: OFF2 (pulses off, motor coasts to a stop) by default; can be changed with P2100/P2101

Likely causes

  • Master (PLC) stopped sending or lost the connection
  • RS485 cable or connection problem
  • Telegram off time P2014[0] too short for the master's cycle

First checks, in this order

  1. Check the USS or Modbus master on RS485 and that it polls the converter.
  2. Check the RS485 cable and connectors.
  3. Check the telegram off time P2014[0] (default 2000 ms; 0 disables the watchdog).

F71: USS setpoint fault (on RS232)

Hits OEE: Availability

What it means: No setpoint telegram arrived from the USS master on RS232 within the telegram off time.[1][2]

Drive response: OFF2 (pulses off, motor coasts to a stop) by default; can be changed with P2100/P2101

Likely causes

  • USS master on RS232 stopped sending or lost the connection

First checks, in this order

  1. Check the USS master on RS232 and its cable.
  2. Check the telegram off time P2014[1] (RS232 channel).

F35: Maximum number of auto restart attempts exceeded

Hits OEE: Availability

What it means: Automatic restart (P1210) tried more restarts than P1211 allows and stopped trying.[1][2]

Drive response: OFF2 (pulses off, motor coasts to a stop) by default; can be changed with P2100/P2101

Likely causes

  • The original fault or supply problem keeps coming back
  • Number of restart attempts P1211 set too low

First checks, in this order

  1. Look in the fault history r0947 for the fault that kept causing restarts and fix it.
  2. Increase the number of restart attempts P1211 (0 to 10, factory default 3).
  3. Check the automatic restart mode in P1210.

F41: Motor data identification failure

Hits OEE: Availability

What it means: The standstill motor data identification (P1900 = 2) did not complete.[1][2]

Drive response: OFF2 (pulses off, motor coasts to a stop); fixed default

Likely causes

  • r0949 = 0: no load applied (motor not connected)
  • r0949 = 1: current limit reached during identification
  • r0949 = 2: identified stator resistance below 0.1% or above 100%
  • r0949 = 30: current controller at voltage limit
  • r0949 = 40: identified data inconsistent, at least one identification failed

First checks, in this order

  1. r0949 = 0: check that the motor is connected to the converter.
  2. r0949 = 1 to 49: check motor data P0304 to P0311 against the rating plate.
  3. Check whether the motor must be wired in star or delta for this supply.

F23: Output current ripple too high

Hits OEE: Availability

What it means: The calculated ripple in the output current passed the safe threshold.[1]

Drive response: OFF2 (pulses off, motor coasts to a stop); fixed default

Likely causes

  • Output phase missing
  • High motor vibration

First checks, in this order

  1. Check the output wiring between converter and motor.
  2. Check the mechanical vibration of the motor.
  3. Check P0296 (response to high output current ripple): 0 no response, 1 alarm A523, 2 fault F23.

F12: Converter temperature signal lost

Hits OEE: Availability

What it means: The converter lost the signal from its heat sink temperature sensor.[1][2]

Drive response: OFF2 (pulses off, motor coasts to a stop) by default; can be changed with P2100/P2101

Likely causes

  • Wire break of the heat sink temperature sensor

First checks, in this order

  1. Contact Siemens service or replace the converter.
  2. Alarm A507 reports the same sensor problem as a warning.

F52: Converter software fault

Hits OEE: Availability

What it means: The converter could not read its own identity, version or data, or the data were invalid.[1][2]

Drive response: OFF2 (pulses off, motor coasts to a stop); fixed default

Likely causes

  • Read failure for converter information
  • Invalid converter data (the r0949 value names the item)

First checks, in this order

  1. Power cycle the converter.
  2. Note the r0949 value for Siemens service.
  3. If the fault returns, contact Siemens service or replace the converter.

F395: Acceptance test/confirmation pending

Hits OEE: Availability

What it means: After a startup clone (or a faulty EEPROM read), the converter wants the parameter set checked and confirmed before it runs a motor.[1][2]

Drive response: OFF2 (pulses off, motor coasts to a stop); fixed default

Likely causes

  • Startup clone from an SD card performed (r0949 = 5)
  • Converter data changed (r0949 = 3 or 4)
  • Previous startup clone aborted (r0949 = 10)
  • Faulty read from the EEPROM (see F51)

First checks, in this order

  1. Check that the current parameter set fits the application.
  2. Confirm the parameter set by acknowledging (clearing) the fault.

F61: SD card parameter cloning failed

Hits OEE: Availability

What it means: Parameter cloning to or from the SD card failed.[1][2]

Drive response: OFF2 (pulses off, motor coasts to a stop); fixed default

Likely causes

  • r0949 = 0: SD card missing, wrong card type, or card failed to initialize for automatic cloning
  • r0949 = 1: converter data cannot be written to the card
  • r0949 = 2: cloning file unavailable
  • r0949 = 3: card cannot read the file
  • r0949 = 4: reading the clone file failed (data or checksum wrong)

First checks, in this order

  1. r0949 = 0: fit an SD card formatted FAT16 or FAT32.
  2. r0949 = 1: check the card (for example, is it full?) and format it again to FAT16 or FAT32.
  3. r0949 = 2: put the correctly named file in the directory /USER/SINAMICS/DATA.
  4. r0949 = 3 or 4: make sure the file is accessible and recreate it.
  5. If the fault came from a startup clone (P8458), it clears only with a power cycle.

F62: Parameter cloning contents invalid

Hits OEE: Availability

What it means: The clone file exists but its contents are not valid (control word corruption).[1][2]

Drive response: OFF2 (pulses off, motor coasts to a stop); fixed default

Likely causes

  • Corrupted or incomplete clone file

First checks, in this order

  1. Copy the file again and make sure the operation completes.

F63: Parameter cloning contents incompatible

Hits OEE: Availability

What it means: The clone file exists but was made on a different converter type.[1][2]

Drive response: OFF2 (pulses off, motor coasts to a stop); fixed default

Likely causes

  • Clone file taken from an incompatible converter type

First checks, in this order

  1. Clone only from a compatible converter type.
  2. If the fault came from a startup clone (P8458), it clears only with a power cycle.

F64: Converter attempted to do an automatic clone during startup

Hits OEE: Availability

What it means: Startup cloning is active and an SD card is fitted, but Clone00.bin is missing from /USER/SINAMICS/DATA.[1][2]

Drive response: OFF2 (pulses off, motor coasts to a stop); fixed default

Likely causes

  • SD card inserted without Clone00.bin in /USER/SINAMICS/DATA
  • Startup cloning still active in P8458 (factory default 2, clone at startup always)

First checks, in this order

  1. If a startup clone is wanted, insert the SD card with the correct file and power cycle.
  2. If not, remove the card and power cycle, or set P8458 = 0 and power cycle.
  3. This fault clears only with a power cycle.

F70: I/O Extension Module communication fault

Hits OEE: Availability

What it means: The converter lost communication with the optional I/O Extension Module.[1]

Drive response: OFF2 (pulses off, motor coasts to a stop); fixed default

Likely causes

  • Module loose or disconnected
  • Faulty I/O Extension Module

First checks, in this order

  1. Switch the converter off before you fit or remove the module.
  2. Reconnect the module and check that it works, then acknowledge the fault.
  3. If the fault persists, replace the module.

F26: Internal error

Hits OEE: Availability

What it means: The converter reported an internal error.[1]

Drive response: OFF2 (pulses off, motor coasts to a stop); fixed default

Likely causes

  • Internal converter error

First checks, in this order

  1. Power cycle the converter.
  2. If the fault returns, contact Siemens service or replace the converter.

F100: Watchdog reset

Hits OEE: Availability

What it means: The converter's internal watchdog reset the processor because of a software error.[1][2]

Drive response: OFF2 (pulses off, motor coasts to a stop); fixed default

Likely causes

  • Software error

First checks, in this order

  1. Contact Siemens service or replace the converter.

F101: Stack overflow

Hits OEE: Availability

What it means: The converter software ran out of stack memory.[1][2]

Drive response: OFF2 (pulses off, motor coasts to a stop); fixed default

Likely causes

  • Software error or processor failure

First checks, in this order

  1. Contact Siemens service or replace the converter.

F200: Script error

Hits OEE: Availability

What it means: The script of the internal converter program stopped because of script errors (other than a forced exit).[1][2]

Drive response: OFF2 (pulses off, motor coasts to a stop) by default; can be changed with P2100/P2101

Likely causes

  • Error in the internal converter program script

First checks, in this order

  1. Check the script and correct it.

F350: Configuration vector for the converter failed

Hits OEE: Availability

What it means: At startup the converter checks its configuration vector against the fitted hardware, and they do not match.[1][2]

Drive response: OFF2 (pulses off, motor coasts to a stop); fixed default

Likely causes

  • r0949 = 13: wrong power module fitted
  • r0949 above 1000: wrong I/O board fitted
  • r0949 = 1, 2, 11 or 12: internal failure

First checks, in this order

  1. r0949 = 13: make sure the right power module is fitted.
  2. Internal failures cannot be fixed on site: contact Siemens service or replace the converter.
  3. This fault needs a power cycle to be acknowledged.

F410: Cavitation protection failure

Hits OEE: Availability

What it means: Pump cavitation protection found conditions that can damage the pump (fluid not flowing enough, which builds heat).[1][2]

Drive response: OFF2 (pulses off, motor coasts to a stop); fixed default

Likely causes

  • Fluid not flowing sufficiently through the pump
  • Cavitation threshold or delay set too tight
  • Feedback sensor not working

First checks, in this order

  1. If cavitation is not really occurring, reduce the cavitation threshold P2361 (default 40%) or increase the cavitation protection time P2362 (default 30 s).
  2. Make sure the sensor feedback works.
  3. P2360 selects the reaction: 1 fault (F410), 2 warning (A930).

F452: Load monitoring trip

Hits OEE: Availability

What it means: The torque and speed curve left the load monitoring envelope, which points to a broken belt or a mechanical fault.[1][2]

Drive response: OFF2 (pulses off, motor coasts to a stop) by default; can be changed with P2100/P2101

Likely causes

  • r0949 = 0: low torque or speed trip (for example a broken belt)
  • r0949 = 1: high torque or speed trip (for example seizure or obstruction)

First checks, in this order

  1. Check the drive train for breakage, seizure or obstruction.
  2. Lubricate if needed.
  3. Check the load monitoring mode P2181 (4 to 6 trip).
  4. Check the envelope: threshold frequencies P2182 to P2184 and torque thresholds P2185 to P2190.
  5. Check the delay time P2192 (default 10 s).

A501: Current limit

Warning: act before it becomes a stop

What it means: Output current has reached the converter's current limit, so the Imax controller is reducing output frequency or voltage.[1][2]

Drive response: Warning only; cannot be acknowledged, clears by itself once the cause is gone

Likely causes

  • Motor power does not match the converter power
  • Motor leads too long
  • Earth faults
  • Ramp-up time too short
  • Small motors (120 W) in FCC mode at light load can draw a high current

First checks, in this order

  1. Work through the F1 checks: P0307 against r0206, cable length, short circuits and earth faults, motor data, P1120 and P1312.
  2. Lengthen the ramp-up time P1120.
  3. Use V/f control for very small motors.

A502: Overvoltage limit

Warning: act before it becomes a stop

What it means: The DC link reached the overvoltage limit. This can happen during ramp-down when the Vdc controller is disabled (P1240 = 0).[1][2]

Drive response: Warning only; cannot be acknowledged, clears by itself once the cause is gone

Likely causes

  • Ramp-down with the Vdc controller disabled (P1240 = 0)
  • Supply voltage too high

First checks, in this order

  1. If the warning shows permanently, check the converter input voltage.
  2. Check P1240 and the ramp-down time P1121.

A503: Undervoltage limit

Warning: act before it becomes a stop

What it means: The supply, and with it the DC link voltage (r0026), dropped below the specified limit.[1][2]

Drive response: Warning only; cannot be acknowledged, clears by itself once the cause is gone

Likely causes

  • Main supply failed or dipped

First checks, in this order

  1. Check the main supply voltage.
  2. Read the DC link voltage r0026.

A505: Converter I2t

Warning: act before it becomes a stop

What it means: Converter overload utilization r0036 passed the I2t warning level P0294 (default 95%). F5 trips if it reaches 100%.[1][2]

Drive response: Warning only; cannot be acknowledged, clears by itself once the cause is gone

Likely causes

  • Load cycle too heavy for the converter

First checks, in this order

  1. Check that the load cycle is within the specified limits.
  2. Watch r0036. The converter reduces its output current as set in P0290 (converter overload reaction).

A511: Motor overtemperature I2t

Warning: act before it becomes a stop

What it means: The motor thermal model reached the warning threshold P0604. F11 follows if P0610 is set to trip.[1][2]

Drive response: Warning only; cannot be acknowledged, clears by itself once the cause is gone

Likely causes

  • Motor overloaded
  • Load cycles or load steps too high

First checks, in this order

  1. Check the motor temperature warning threshold P0604 and the motor surrounding temperature P0625.
  2. Check the rating plate data. If wrong, run quick commissioning again, then motor identification (P1900 = 2) for accurate data.
  3. Check that the motor weight P0344 is reasonable.
  4. For a motor that is not a Siemens standard motor, adjust the overtemperatures P0626, P0627 and P0628.

A504: Converter overtemperature

Warning: act before it becomes a stop

What it means: The heat sink or chip junction temperature, or the allowed junction temperature change, passed its warning level. The converter reduces pulse frequency and/or output frequency depending on P0290.[1][2]

Drive response: Warning only; cannot be acknowledged, clears by itself once the cause is gone

Likely causes

  • Surrounding temperature too high
  • Heavy load or load steps
  • Fan not working

First checks, in this order

  1. Read r0037[0] (heat sink) and r0037[1] (chip junction) temperatures.
  2. Check that the surrounding temperature is within the specified limits.
  3. Check the load conditions and load steps.
  4. Check that the fan turns while the converter runs.

A506: IGBT junction temperature rise warning

Warning: act before it becomes a stop

What it means: Overload warning: the difference between the heat sink and the IGBT junction temperature passed the warning limit.[1][2]

Drive response: Warning only; cannot be acknowledged, clears by itself once the cause is gone

Likely causes

  • Load steps or shock loads too high

First checks, in this order

  1. Check that load steps and shock loads are within the specified limits.

A507: Converter temperature signal lost

Warning: act before it becomes a stop

What it means: The heat sink temperature signal is lost; the sensor may have come loose.[1][2]

Drive response: Warning only; cannot be acknowledged, clears by itself once the cause is gone

Likely causes

  • Heat sink temperature sensor fallen off or broken

First checks, in this order

  1. Contact Siemens service or replace the converter.

A910: Vdc_max controller de-activated

Warning: act before it becomes a stop

What it means: The Vdc_max controller has been switched off, so the converter can no longer stretch the ramp-down to prevent overvoltage.[1][2]

Drive response: Warning only; cannot be acknowledged, clears by itself once the cause is gone

Likely causes

  • Supply voltage (P0210) permanently too high
  • Motor driven by an active load, putting it into regenerative mode
  • Very high load inertia during ramp-down

First checks, in this order

  1. Check that the input voltage is within range and that P0210 matches it.
  2. Check that the load matches the converter.
  3. In some cases, fit a braking resistor.
  4. If A910 appears in standby and an ON command follows, the Vdc_max controller (A911) stays off until A910 is cleared.

A911: Vdc_max controller active

Warning: act before it becomes a stop

What it means: The Vdc_max controller is working to keep the DC link voltage (r0026) below the level in r1242, which lengthens the ramp-down.[1][2]

Drive response: Warning only; cannot be acknowledged, clears by itself once the cause is gone

Likely causes

  • Ramp-down time too short for the load inertia
  • Supply voltage too high

First checks, in this order

  1. Check that the supply voltage is within the rating plate limits.
  2. Match the ramp-down time P1121 to the load inertia.
  3. Higher inertia needs longer ramp times; otherwise fit a braking resistor.

A912: Vdc_min controller active

Warning: act before it becomes a stop

What it means: The DC link voltage (r0026) fell below the level in r1246, so kinetic buffering uses motor energy to hold it up, which slows the motor down.[1][2]

Drive response: Warning only; cannot be acknowledged, clears by itself once the cause is gone

Likely causes

  • Short mains dip or failure
  • Fast ramp-up
  • Shock load

First checks, in this order

  1. Check the converter input voltage.
  2. If it appears during ramp-up, increase the ramp-up time P1120.
  3. Check for shock loads (see F3).

A922: No load applied to converter

Warning: act before it becomes a stop

What it means: The converter sees no load, so some functions may not work as they do under normal load.[1][2]

Drive response: Warning only; cannot be acknowledged, clears by itself once the cause is gone

Likely causes

  • Motor not connected or output circuit open

First checks, in this order

  1. Check that the motor is connected to the converter.

A930: Cavitation protection warn

Warning: act before it becomes a stop

What it means: Cavitation protection found conditions for possible pump cavitation damage (P2360 = 2 selects this warning instead of fault F410).[1][2]

Drive response: Warning only; cannot be acknowledged, clears by itself once the cause is gone

Likely causes

  • Fluid not flowing sufficiently through the pump
  • Cavitation threshold or delay set too tight

First checks, in this order

  1. See F410: check the threshold P2361, the protection time P2362 and the feedback sensor.

A936: PID autotuning active

Warning: act before it becomes a stop

What it means: PID autotuning (P2350) is selected or running.[1][2]

Drive response: Warning only; cannot be acknowledged, clears by itself once the cause is gone

Likely causes

  • PID autotuning enabled in P2350

First checks, in this order

  1. Let the autotuning finish; the warning then clears.

A535: Braking resistor overload

Warning: act before it becomes a stop

What it means: The braking resistor is overloaded.[1][2]

Drive response: Warning only; cannot be acknowledged, clears by itself once the cause is gone

Likely causes

  • Braking energy too large
  • Braking resistor not suited to the application

First checks, in this order

  1. Reduce the braking energy, for example with a longer ramp-down time P1121.
  2. Use a braking resistor with a higher rating.

A541: Motor data identification active

Warning: act before it becomes a stop

What it means: Motor data identification (P1900) is selected or running. The next ON command starts the standstill measurement.[1][2]

Drive response: Warning only; cannot be acknowledged, clears by itself once the cause is gone

Likely causes

  • P1900 set to 2 (identification of all parameters at standstill)

First checks, in this order

  1. Give the ON command and let the identification finish; P1900 returns to 0 when done.
  2. Make sure any motor holding brake is released, and that quick commissioning was done first.

A952: Load monitoring warning

Warning: act before it becomes a stop

What it means: Load conditions on the motor point to a broken belt or a mechanical fault (P2181 set to a warning mode).[1][2]

Drive response: Warning only; cannot be acknowledged, clears by itself once the cause is gone

Likely causes

  • Broken belt, seizure or obstruction in the drive train

First checks, in this order

  1. See F452: check the drive train, P2181 and the envelope P2182 to P2190, and the delay P2192.

A523: Output current ripple too high

Warning: act before it becomes a stop

What it means: The calculated ripple in the output current passed the safe threshold (P0296 = 1 selects this alarm).[1]

Drive response: Warning only; cannot be acknowledged, clears by itself once the cause is gone

Likely causes

  • Loss of one of the output phases
  • High motor vibration

First checks, in this order

  1. Check the output wiring.
  2. Check the mechanical vibration of the motor.

A921: Analog output parameters not set properly

Warning: act before it becomes a stop

What it means: The analog output scaling parameters P0777 and P0779 are set to identical values, which gives an illogical result.[1][2]

Drive response: Warning only; cannot be acknowledged, clears by itself once the cause is gone

Likely causes

  • P0777 and P0779 set to the same value
  • Analog output settings do not match the analog output type

First checks, in this order

  1. Set P0777 and P0779 to different values.
  2. Check that the output settings match the analog output type.

A923: Both JOG left and JOG right are requested

Warning: act before it becomes a stop

What it means: JOG right and JOG left (P1055 and P1056) are both requested, which freezes the ramp output frequency at its present value.[1][2]

Drive response: Warning only; cannot be acknowledged, clears by itself once the cause is gone

Likely causes

  • Both JOG commands active at the same time

First checks, in this order

  1. Do not press JOG right and JOG left at the same time.
  2. Check the sources wired to P1055 and P1056.

A600: RTOS overrun warning

Warning: act before it becomes a stop

What it means: An internal time slice of the converter's real-time operating system overran.[1][2]

Drive response: Warning only; cannot be acknowledged, clears by itself once the cause is gone

Likely causes

  • Internal time slice overrun

First checks, in this order

  1. Contact Siemens service.

Log it, or the same alarm comes back

A fault stops the inverter and with it the conveyor, pump or fan the line depends on, so in OEE terms it is a breakdown. An alarm lets it keep running, but its cause often becomes a fault later in the shift. Log faults with the minutes lost and alarms as early signs.

  • Reason code: the code plus the drive, for example V20 F11, mixer agitator motor, so a motor overtemperature that trips on every long batch shows up as a pattern.
  • Loss bucket: a stop that needs a reset, a part or a technician is an availability loss (breakdown). Stops shorter than your micro-stop threshold go to performance (minor stops). The six big losses page shows where each one belongs.
  • What to count: how often each code fires per week and the minutes it costs. Two numbers a week turn "that alarm comes up sometimes" into a ranked list. The MTBF and MTTR calculator and the downtime cost calculator do the math.

The free OEE tracker logs each stop with its reason and turns the week into a downtime Pareto, so the code that costs the most rises to the top.

For the SINAMICS G120 and S120 drive faults, fabrico.io has the SINAMICS drive fault codes guide. A fault code tells you what the inverter measured, not what happened at the machine in the seconds before. Fabrico's camera-based OEE software syncs line camera video with machine data, so you can replay the moment the line stopped next to the fault.

Frequently asked questions

What does F11 mean on a Siemens V20?

F11 is Motor overtemperature. The converter's motor thermal model calculates that the motor is too hot; the trip level is 10% above the warning threshold P0604, and alarm A511 normally shows first. Check the load and load steps, the motor overtemperature values P0626 to P0628 and P0604. Small motors running below 15 Hz can trip F11 even when the motor is cool: if the current is within the rating plate value and the motor is physically within its temperature limits, Siemens says to set P0335 = 1. P0610 sets how the converter reacts at the warning threshold.

How do I reset a fault on a SINAMICS V20?

Fix the cause first, then press OK on the built-in BOP while the fault code is shown. You can also acknowledge externally: digital input 3 is set to fault acknowledge by default (P0703 = 9, source P2103), and any digital input can be given function 9. Pressing M only hides the fault; the fault icon stays until it is acknowledged. Some faults clear only after a power cycle, for example F51, F64 and F350, and F5 cannot be cleared until r0036 drops below P0294. Automatic restart P1210 can also reset faults after power on or after a fault.

What is the difference between F and A codes on the V20?

An F code is a fault: the converter stops the motor (default reaction OFF2, the motor coasts to a stop) and the fault must be acknowledged. An A code is an alarm, or warning: the converter keeps running, sometimes with reduced current or frequency, and the alarm clears by itself once the cause is gone; it cannot be acknowledged. Some codes belong together: A505 warns before F5 trips and A511 before F11, while A930 and F410, and A952 and F452, are the warning and trip versions of the same pump and load protections. The fault history is in r0947 and the warning history in r2110.

What does F60 mean on a V20?

F60 is Asic timeout, an internal communication failure inside the converter. r0949 shows 0 for a hardware-reported link failure and 1 for a software-reported one. If F60 appears now and then, Siemens points to EMC problems: improve shielding, grounding and cable separation, and use an EMC filter. If F60 appears as soon as mains is applied and an ON command is given, contact Siemens service or replace the converter.

What do F20 and F6 mean on a SINAMICS V20?

F20 is DC ripple too high: the ripple on the DC link passed the safe limit, most often because one mains input phase is missing. Check the supply wiring, the fuses and all three phase voltages. F6 is Chip temperature rise exceeds critical levels: the IGBT chips heated too fast, usually from a hard start, a big load step or a short ramp-up. Increase the ramp-up time P1120, check motor power P0307 against converter power r0206, and use P0290 = 0 or 2 so the converter reduces its output instead of tripping.

Sources

Codes and meanings follow the manufacturer documentation below. Wording is ours, simplified for the shop floor; the manual for your exact model and software version wins if it differs.

  1. SINAMICS V20 Converter Operating Instructions, Edition 12/2024, A5E34559884-017 (Siemens web version, entry 109977897)
  2. SINAMICS V20 Inverter Operating Instructions, Edition 11/2016, A5E34559884-006 (PDF)

See the moment the drive tripped

Fabrico, a light MES with computer vision, syncs camera footage with machine and timeline data, so you can replay the exact moment the line stopped and review the cause next to the drive's fault. Cameras also catch short stops and a line that is switched on but not producing, the losses nobody writes down. Machines connect through a PLC, a Fabrico IoT device or an AI camera.

Book a Fabrico demo
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Related tools: full troubleshooting directory · OEE calculator · downtime cost · MTBF / MTTR · glossary

OEE essentials: OEE calculator · What is OEE · How to improve OEE · Six big losses · Availability · TEEP · Cost of downtime · OEE benchmark · Free OEE tracker · Free OEE software · How to track downtime · How to implement OEE · Light MES vs full MES