Siemens MICROMASTER 440 Fault Codes

F0001: Overcurrent

What it means: The inverter measured too much output current and tripped to protect its power stage.^[1][2][4][5]

Also on: MM420, MM430 (same code and name)

Likely causes

• Short circuit at the output, in the motor cable or in the motor
• Ground fault in the motor or motor cable
• Motor rated higher than the inverter (motor power P0307 greater than inverter power r0206)
• Motor overloaded or rotor locked, acceleration too fast, or a defective output stage

First checks, in this order

1. Check the motor cable and motor for short circuits and ground faults, and check the cable length is within the limits
2. Compare the rating plate with motor data P0304 to P0311 and confirm P0307 is not larger than r0206
3. Check the stator resistance value P0350 and that the motor is not jammed or overloaded
4. Lengthen the ramp-up time P1120 and reduce boost (V/f: P1311, P1312; vector: P1610, P1611)

F0002: Overvoltage

What it means: The DC link voltage (r0026) rose above the overvoltage threshold, usually because the motor fed energy back into the drive.^[1][2][4][5]

Also on: MM420, MM430 (same code and name)

Likely causes

• Motor working as a generator while decelerating faster than the load inertia allows
• An active load driving the motor (regenerative operation)
• Supply voltage too high
• Ground fault

First checks, in this order

1. Check the supply voltage is within the rating plate range and matches P0210
2. Check the Vdc_max controller is enabled and set up in P1240 (1 or 3 enables it)
3. Lengthen the ramp-down time P1121 (and the OFF3 ramp P1135) to suit the load inertia
4. If the braking energy is still too high, fit a braking resistor and enable dynamic braking in P1237

F0003: Undervoltage

What it means: The DC link voltage dropped too low, usually because the supply failed or dipped.^[1][2][4][5]

Also on: MM420, MM430 (same code and name)

Likely causes

• Supply voltage failed or dipped (brown-out)
• Shock load outside the permitted limits

First checks, in this order

1. Measure the supply voltage and check it is within the permitted range and matches P0210
2. Check the supply for short interruptions and voltage dips
3. If short dips cannot be avoided, enable kinetic buffering (Vdc_min controller) with P1240 = 2

F0004: Inverter overtemperature

What it means: The inverter heatsink got too hot and the drive tripped.^[1][2][4][5]

Also on: MM420, MM430 (same code and name)

Likely causes

• Inadequate cooling or blocked air flow
• Fan not turning
• Ambient temperature too high
• Load or load duty cycle too high

First checks, in this order

1. Check the fan turns when the inverter is running
2. Check the pulse frequency P1800 is at the factory setting and reset it if not
3. Check the ambient temperature and cabinet ventilation are within limits, and reduce the load if needed
4. On frame sizes FX and GX read r0949: 1 = rectifier, 2 = ambient, 3 = EBOX overtemperature

F0005: Inverter I2T

What it means: The inverter's calculated overload (I2t) reached 100 percent, so it tripped to protect itself.^[1][2][4][5]

Also on: MM420, MM430 (same code and name)

Likely causes

• Inverter overloaded
• Load duty cycle too high
• Motor power P0307 greater than inverter power r0206

First checks, in this order

1. Read the inverter overload utilization in r0036
2. Check the load duty cycle is within the permitted limits
3. Check P0307 against r0206; if the motor is larger than the inverter, use a smaller motor or a larger inverter

F0011: Motor overtemperature

What it means: The motor temperature, from the thermal model or a sensor, passed the trip level.^[1][2][4][5]

Also on: MM420 (named Motor overtemperature I2T, checks the thermal time constant P0611), MM430 (same name)

Likely causes

• Motor overloaded
• Load cycle too heavy for the motor
• Wrong motor data or wrong temperature thresholds set

First checks, in this order

1. Check the motor load cycle
2. Check the rated motor overtemperatures P0626 to P0628 and the warning threshold P0604
3. If P0601 = 0 or 1: check rating plate data (redo quick commissioning if wrong), run motor identification P1910 = 1 and check motor weight P0344
4. If P0601 = 2: check the temperature in r0035 is plausible and that the sensor is a KTY84 (other sensors are not supported)

F0012: No inverter temperature signal

What it means: The inverter lost the signal from its own heatsink temperature sensor (the 12/02 manual calls it Inverter temp. signal lost).^[1][2][5]

Also on: MM430 (same code and name)

Likely causes

• Wire break of the heatsink temperature sensor inside the inverter

First checks, in this order

1. Acknowledge the fault and power cycle the drive to see if it returns
2. If it returns, the manual's remedy is to replace the inverter

F0015: No motor temperature signal

What it means: The signal from the motor temperature sensor was lost, and temperature monitoring switches over to the thermal motor model.^[1][2][5]

Also on: MM430 (same code and name)

Likely causes

• Motor temperature sensor short circuited
• Motor temperature sensor or its wiring open circuit

First checks, in this order

1. Check the sensor type in P0601 matches the sensor fitted (2 = KTY84, which is the type whose loss can be detected)
2. Check the sensor wiring between the motor and the inverter for breaks or shorts

F0020: Line supply phase missing

What it means: One of the three supply phases is missing while the pulses are enabled and the drive is loaded (the 12/02 manual calls it Mains Phase Missing).^[1][2][5]

Also on: MM430 (same code and name)

Likely causes

• One of the three input phases lost
• Loose or faulty power connection on the supply side

First checks, in this order

1. Measure all three supply phases at the inverter input terminals
2. Check the input power wiring and connections

F0021: Ground fault

What it means: The sum of the three phase currents is above 5 percent of the inverter rated current, which points to current leaking to ground (only on units with 3 current sensors: frame sizes D to F, FX, GX; the 12/02 manual calls it Earth fault).^[1][2][5]

Also on: MM430 (same code and name)

Likely causes

• Ground fault in the motor or motor cable
• Faulty connection in the motor terminal box or at the inverter output

First checks, in this order

1. Check the connections in the motor terminal box
2. Check the motor cable connections at the inverter

F0022: Hardware monitoring active

What it means: The power module reported a hardware fault (r0947 = 22 with r0949 = 1) and the drive cannot tell which one it was (the 12/02 manual calls it Powerstack fault).^[1][2][5]

Also on: MM430 (same code and name)

Likely causes

• DC link overcurrent from an IGBT short circuit
• Braking chopper short circuit
• Ground fault
• I/O module not inserted correctly (on FX/GX, r0949 = 12, 13 or 14 is a UCE fault and 21 an I2C bus error)

First checks, in this order

1. Decide whether the fault is permanent (trips on every start) or sporadic
2. Check the I/O module is fully pressed home
3. Disconnect the motor cable and retry; if it still trips with all external cables except the supply removed, the drive is very likely defective
4. If sporadic, treat it as overcurrent: look for load jumps or jams, very short ramp-up times, poor vector tuning or a braking resistor with too low a resistance

F0023: Output fault

What it means: One output phase to the motor is not connected correctly.^[1][2][5]

Also on: MM430 (same code and name)

Likely causes

• One motor phase disconnected
• Loose connection in the motor terminal box or at the inverter output terminals

First checks, in this order

1. Check the connections in the motor terminal box
2. Check the motor cable connections at the inverter terminals U, V, W

F0024: Rectifier temperature too high

What it means: The input rectifier of the inverter got too hot.^[1]

Likely causes

• Inadequate cooling
• Fan not working
• Ambient temperature too high

First checks, in this order

1. Check the fan turns when the inverter is powered up (watch for alarms A0520 and A0521)
2. Check the pulse frequency P1800 is at the factory setting and reset it if not
3. Check the ambient temperature is within the permitted limits

F0030: Fan failed

What it means: The inverter cooling fan has stopped working (the 12/02 manual calls it Fan has failed).^[1][2]

Likely causes

• Fan no longer works

First checks, in this order

1. Check whether the fan turns
2. Replace the fan; the fault cannot be suppressed while a BOP or AOP is connected

F0035: Restart after n

What it means: Automatic restart gave up after the number of restart attempts set in P1211 (the 12/02 manual calls it Auto restart after n).^[1][2][4][5]

Also on: MM420, MM430 (same code and name)

Likely causes

• Automatic restart (P1210) used up all attempts set in P1211
• The fault that caused the restarts is still present

First checks, in this order

1. Read the fault history r0947 to find the fault behind the restarts
2. Fix that fault, then reset the fault memory or use power on / stop to acknowledge
3. Check the automatic restart settings P1210 and P1211

F0040: Fault, for automatic calibration

What it means: The automatic calibration of the analog inputs and outputs or of the current sensing failed; this is done once in the factory, so the fault is not expected in normal operation.^[1]

Likely causes

• Calibration error of the analog inputs/outputs
• Calibration error of the actual current sensing

First checks, in this order

1. Acknowledge the fault and power cycle the drive
2. If it stays, the manual's remedy is to change the drive

F0041: Failure, motor data identification

What it means: The motor data identification run (P1910) failed, and the fault value r0949 says why.^[1][2][4][5]

Also on: MM420, MM430 (same code and name)

Likely causes

• r0949 = 0: no load, motor not connected
• r0949 = 1: current limit reached during the identification run
• r0949 = 2 to 40: identified motor values out of range or inconsistent, linked to wrong motor data or wrong star/delta connection

First checks, in this order

1. Read the fault value in r0949
2. If r0949 = 0: check the motor is connected to the inverter
3. If r0949 = 1 to 40: check motor data P0304 to P0311 against the rating plate
4. Check the motor is connected in the right configuration (star or delta)

F0042: Fault/error when optimizing the speed controller

What it means: The automatic speed controller optimisation (P1960) failed (the 12/02 manual calls it Speed Control Optimisation Failure).^[1][2]

Likely causes

• r0949 = 0: timed out while waiting for a stable speed
• r0949 = 1: inconsistent readings

First checks, in this order

1. Read the fault value in r0949
2. Check the motor and load can reach a stable speed during the optimisation run
3. Repeat the optimisation via P1960 (alarm A0542 shows while it runs)

F0051: Parameter EEPROM fault

What it means: Reading or writing the parameters to the non-volatile memory (EEPROM) failed.^{[1][2][3][4][5]}

Also on: MM420, MM430 (same code and name)

Likely causes

• Read or write error while saving parameters to the EEPROM

First checks, in this order

1. Reset to factory settings (P0010 = 30, then P0970 = 1) and parameterize the drive again
2. If it comes back, change the drive or contact Siemens service

F0052: Power stack fault

What it means: The control board could not read valid data from the power module.^[1][2][4][5]

Also on: MM420, MM430 (same code and name)

Likely causes

• Read error of the power module data
• Invalid power module data

First checks, in this order

1. Acknowledge the fault and power cycle the drive
2. If it returns, treat it as a hardware defect: change the drive or contact Siemens service

F0053: I/O EEPROM fault

What it means: The EEPROM on the I/O module could not be read or holds invalid data.^[1][2][5]

Also on: MM430 (same code and name)

Likely causes

• Read error of the I/O EEPROM
• Invalid I/O data
• I/O module not installed correctly

First checks, in this order

1. Check the I/O data and repeat the operation
2. Check the I/O module is correctly installed in the inverter
3. Replace the I/O module if the fault stays

F0054: Incorrect I/O module

What it means: The wrong I/O module is fitted, or no ID could be read from it (the 12/02 manual calls it Wrong IO Board).^[1][2][5]

Also on: MM430 (same code and name)

Likely causes

• Incorrect I/O module inserted
• No ID found on the I/O module, no data

First checks, in this order

1. Check the I/O data and repeat the operation
2. Check the I/O module type and that it is correctly installed
3. Replace the I/O module if needed

F0060: Asic time slice overflow

What it means: An internal communication error happened inside the inverter electronics (the 12/02 manual calls it Asic Timeout).^{[1][2][4][5][6]}

Also on: MM420, MM430 (same code and name)

Likely causes

• Internal communications failure

First checks, in this order

1. Acknowledge the fault and power cycle the drive
2. If it occurs again, replace the inverter or contact Siemens service

F0070: CB setpoint fault

What it means: No setpoint arrived from the communication board (fieldbus option) within the telegram off time.^[1][2][4][5]

Also on: MM420, MM430 (same code and name)

Likely causes

• Fieldbus communication interrupted
• Communication partner (master, PLC) not sending

First checks, in this order

1. Check the communication board (CB), its connector and cable
2. Check the communication partner is running and sending telegrams
3. Check the CB telegram off time P2040 (0 disables this watchdog)

F0071: USS (BOP link) setpoint fault

What it means: No setpoint arrived via USS on the BOP link (RS232) within the telegram off time.^[1][2][4][5]

Also on: MM420, MM430 (same code and name)

Likely causes

• USS master on the BOP link stopped sending
• Connection on the BOP link interrupted

First checks, in this order

1. Check the USS master
2. Check the connection on the BOP link
3. Check the USS telegram off time P2014 index 1 (BOP link)

F0072: USS (COMM link) setpoint fault

What it means: No setpoint arrived via USS on the COM link (RS485) within the telegram off time.^[1][2][4][5]

Also on: MM420, MM430 (same code and name)

Likely causes

• USS master on the COM link stopped sending
• RS485 connection interrupted

First checks, in this order

1. Check the USS master
2. Check the RS485 wiring to the COM link terminals
3. Check the USS telegram off time P2014 index 0 (COM link)

F0080: ADC input signal lost

What it means: An analog input with monitoring enabled lost its signal or went outside its limits (the 12/02 manual calls it ADC lost input signal).^{[1][2][4][5][6]}

Also on: MM420, MM430 (same code and name)

Likely causes

• Wire break on the analog input
• Signal outside the limit values

First checks, in this order

1. Check the analog input wiring and the signal source
2. Check P0756 (settings 1 and 3 enable monitoring) and the deadband P0761: the fault trips when the input falls below 50 percent of the deadband
3. Check the DIP switch for that input matches voltage or current input, and the delay P0762 before the fault reacts

F0085: External fault

What it means: An external fault was triggered through a command input, usually a terminal.^[1][2][4][5]

Also on: MM420, MM430 (same code and name)

Likely causes

• External fault signal from a device wired to a digital input
• Input assigned as external fault source in P2106

First checks, in this order

1. Check which input is set as the external fault source in P2106
2. Check the device and wiring connected to that input and clear its fault
3. Inhibit that terminal input if it should not trigger a fault, then acknowledge

F0090: Signal loss, encoder

What it means: The encoder signal was lost, or the difference between setpoint and actual frequency became too large (the 12/02 manual calls it Encoder feedback loss).^[1][2][5]

Also on: MM430 (same code and name)

Likely causes

• Encoder signal between encoder and inverter interrupted
• Encoder faulty
• Too large a difference between setpoint and actual frequency
• Encoder selected in P0400 but no encoder fitted

First checks, in this order

1. If no encoder is fitted, set P0400 = 0 and select sensorless vector control (P1300 = 20 or 22)
2. Check the encoder cable and connections to the inverter
3. Test the encoder: set P1300 = 0, run at a fixed speed and check the encoder signal in r0061
4. Increase the encoder signal thresholds P0492 and P0494

F0101: Stack overflow

What it means: A software error or processor failure happened in the control electronics.^{[1][2][4][5][6]}

Also on: MM420, MM430 (same code and name)

Likely causes

• Software error
• Processor failure

First checks, in this order

1. Power cycle the drive and run the self-test routines
2. If it comes back, change the inverter

F0221: PID feedback below the minimum value

What it means: The PID feedback signal dropped below the minimum set in P2268.^[1][2][4][5]

Also on: MM420, MM430 (same code and name)

Likely causes

• PID feedback below the minimum value P2268
• P2268 or the feedback gain not set to suit the sensor

First checks, in this order

1. Check the feedback sensor signal
2. Check and change the minimum value P2268
3. Set the PID feedback gain P2269

F0222: PID feedback above maximum value

What it means: The PID feedback signal rose above the maximum set in P2267.^[1][2][4][5]

Also on: MM420, MM430 (same code and name)

Likely causes

• PID feedback above the maximum value P2267
• P2267 or the feedback gain not set to suit the sensor

First checks, in this order

1. Check the feedback sensor signal
2. Check and change the maximum value P2267
3. Set the PID feedback gain P2269

F0422: No load applied to inverter

What it means: The inverter sees no load at its output, so some functions may not work as they do under normal load.^[1][4][5]

Also on: MM420, MM430 (same code and name)

Likely causes

• No motor or load connected to the inverter output

First checks, in this order

1. Check a motor is connected to the output terminals U, V, W
2. Check the motor cable connections at the inverter and the motor (alarm A0922 is the matching warning)

F0450: Failure BIST tests

What it means: A built-in self test failed, and the fault value r0949 shows which part (the 12/02 manual calls it BIST Tests Failure).^[1][2][4][5]

Also on: MM420, MM430 (same code and name)

Likely causes

• r0949 = 1: power module self test failed; r0949 = 2: control module self test failed
• r0949 = 4: several function tests failed
• r0949 = 8: I/O module tests failed (MM420 only)
• r0949 = 16: internal RAM failed the switch-on test

First checks, in this order

1. Read the fault value in r0949
2. Note that the drive may still run but some functions will not work correctly
3. Replace the drive

F0452: Load torque fault detected

What it means: Load torque monitoring found load conditions that point to a broken belt or another mechanical fault (the 12/02 manual calls it Belt Failure Detected).^[1][2][5]

Also on: MM430 (same code and name)

Likely causes

• Belt failure
• Breakage, seizure or obstruction in the mechanical drive train
• Torque monitoring thresholds not set to suit the machine

First checks, in this order

1. Inspect the drive train for breakage, seizure or obstruction, and lubricate it if needed
2. If an external encoder is used, check the delay time P2192
3. Check the torque envelope: threshold frequencies P2182 to P2184 and upper/lower torque thresholds P2185 to P2190
4. Check the belt failure detection mode P2181

F0453: Motor stalled

What it means: The drive detected that the motor stalled.^[1]

Likely causes

• Ramp-up or ramp-down too steep
• Inverter switched onto a motor that was already turning, without flying restart
• Motor wrongly connected or too small
• Voltage boost P1611 too low in sensorless vector control

First checks, in this order

1. Check the motor connections
2. Increase the ramp-up time P1120 or the ramp-down time P1121
3. Enable flying restart in P1200 if the motor may already be turning at start
4. In sensorless vector control raise P1611, or use vector control with encoder or V/f control (P1300 less than 20)

A0501: Current limit value

What it means: The inverter output current has reached the current limit (the 12/02 manual calls it Current Limit).^[1][2][4][5]

Also on: MM420, MM430 (same code and name)

Likely causes

• Motor power does not match the inverter power
• Motor cable too long
• Short circuit or ground fault in the motor or cable
• Motor overloaded or rotor locked, or ramp-up time P1120 too short

First checks, in this order

1. Check that P0307 matches r0206
2. Check cable length limits and look for short circuits or ground faults
3. Check the motor parameters and the stator resistance P0350
4. Lengthen the ramp-up time P1120 and reduce boost (V/f: P1311, P1312; vector: P1610, P1611)

A0502: Overvoltage limit value

What it means: The DC link voltage (r0026) has reached the overvoltage limit (r0026 above r1242), the warning stage of an overvoltage condition.^[1][2][4][5]

Also on: MM420, MM430 (same code and name)

Likely causes

• Supply voltage too high if the alarm stays on
• Vdc_max controller switched off (P1240 = 0) during ramp-down
• Short ramp times with large flywheel masses (high inertia)

First checks, in this order

1. If the alarm is shown all the time, check the inverter input voltage against P0210
2. Check the Vdc_max controller is enabled in P1240
3. Lengthen the ramp-down time P1121 to suit the load inertia

A0503: Undervoltage limit value

What it means: The supply failed or the supply voltage, and with it the DC link voltage (r0026), is below the limit.^[1][2][4][5]

Also on: MM420, MM430 (same code and name)

Likely causes

• Supply failed
• Supply voltage too low or dipping

First checks, in this order

1. Check the line voltage at the inverter input
2. Check the supply for short interruptions and voltage dips
3. Consider kinetic buffering with P1240 = 2 if short dips cannot be avoided

A0504: Inverter overtemperature

What it means: The heatsink temperature passed the warning threshold, and the drive may lower the pulse frequency and/or output frequency depending on its overload reaction setting.^[1][2][4][5]

Also on: MM420, MM430 (same code and name)

Likely causes

• Ambient temperature too high
• Load or load duty cycle too high
• Fan not turning

First checks, in this order

1. Check the ambient temperature is within the permitted limits
2. Check the load and load duty cycle are within limits
3. Check the fan turns and the pulse frequency P1800 is at the factory setting
4. Check the overload reaction P0290 and the warning margin P0292

A0505: Inverter I2T

What it means: The inverter overload warning level P0294 was exceeded (see utilization r0036), and output or pulse frequency may be reduced depending on P0290.^[1][2][4][5]

Also on: MM420, MM430 (same code and name)

Likely causes

• Inverter overloaded
• Load duty cycle too high
• Motor power P0307 larger than inverter power r0206

First checks, in this order

1. Read the overload utilization in r0036
2. Check the load duty cycle is within the permitted limits
3. Check P0307 against r0206

A0511: Motor overtemperature

What it means: The motor temperature passed the warning threshold P0604, which comes before an F0011 trip (the 01/06 list shows A0510 under the same entry).^[1][2][4][5]

Also on: MM420 (named Motor overtemperature I2T), MM430 (same name)

Likely causes

• Motor overloaded
• Load duty cycle exceeded

First checks, in this order

1. Check the warning threshold P0604 and the motor ambient temperature P0625
2. If P0601 = 0 or 1: check rating plate data, run motor identification P1910 = 1 and check motor weight P0344
3. If the motor is not a standard Siemens motor, adjust the permitted overtemperatures P0626 to P0628
4. If P0601 = 2: check r0035 is plausible and that a KTY84 sensor is used

A0535: Brake resistor hot

What it means: The load duty cycle of the braking resistor was exceeded, so braking is automatically limited to the duty cycle set in P1237.^[1][2]

Likely causes

• Braking resistor duty cycle exceeded
• Braking resistor rated too small for the braking energy

First checks, in this order

1. Lengthen the ramp-down time P1121
2. Check the duty cycle setting P1237 matches the fitted resistor
3. Use a braking resistor with a higher power rating or duty cycle

A0910: Vdc-max controller disabled/switched-out

What it means: The Vdc_max controller switched itself off because it could not keep the DC link voltage (r0026) within limits (the 12/02 manual calls it Vdc-max controller de-activated).^[1][2][4][5]

Also on: MM420, MM430 (same code and name)

Likely causes

• Supply voltage permanently too high
• Motor driven by an active load and running regenerative
• Very high load torque or inertia during short ramp-downs (P1121)

First checks, in this order

1. Check the input voltage is within range and matches P0210
2. Check the load duty cycle and load limits are within the permitted limits
3. Check the ramp-down time P1121 suits the load inertia

A0911: Vdc-max controller active

What it means: The Vdc_max controller is working and is stretching the ramp-down time automatically to keep the DC link voltage (r0026) within limits.^[1][2][4][5]

Also on: MM420, MM430 (same code and name)

Likely causes

• Ramp-down time P1121 shorter than the load inertia allows
• Regenerative energy from the motor during braking

First checks, in this order

1. No action is needed if the longer stopping time is acceptable
2. If the stop takes too long, check P1121 against the load inertia and consider a braking resistor with dynamic braking (P1237)

A0922: No load at the inverter

What it means: No load is connected to the inverter, so some functions may behave differently than under normal load (the 12/02 manual calls it No load applied to inverter).^[1][2][4][5]

Also on: MM420, MM430 (same code and name)

Likely causes

• No motor or load connected to the inverter output

First checks, in this order

1. Check a motor is connected to U, V, W
2. Check the motor cable connections at the inverter and the motor