Problems on this page:
Reading drifting over time
Hits OEE: Quality
Symptoms: The pressure reading moves away from a reference gauge over weeks or months.
Sensor ageing or overpressure damage
Check the transmitter against a calibrated reference and replace it if it cannot be trimmed back.
Temperature effects on the sensor
Check whether the transmitter is mounted on hot or cold pipework without an impulse line or siphon.
Impulse line partly blocked
Blow down or clean the impulse line and check its isolation valve.
Diaphragm seal or capillary damaged
Inspect the diaphragm seal for dents and the capillary for kinks.
Prevention: Transmitters checked against a reference at the interval the quality system sets.
Reading stuck or not changing
Hits OEE: Availability
Symptoms: The reading stays flat while the process pressure clearly changes.
Isolation valve closed after maintenance
Check the root valve and the manifold valves are open.
Impulse line blocked or frozen
Clear the line and add trace heating where it freezes.
Transmitter in fixed output or test mode
Check the transmitter mode with the configuration tool.
Sensor failed
Read the transmitter diagnostics and replace it if the sensor has failed.
Prevention: Process trends checked for flat lines on critical points.
Noisy or spiking reading
Hits OEE: Quality
Symptoms: The signal spikes or is noisy, and alarms or control loops react to it.
Pressure pulses from pumps or valves
Increase the damping or fit a snubber.
Electrical noise on the signal cable
Check the cable route, screen and earthing.
Air in a liquid impulse line or liquid in a gas line
Vent or drain the impulse line, and check its slope.
Loose connection in the loop
Check the terminals in the loop.
Prevention: Damping settings recorded per loop.
Wrong range or units
Hits OEE: Quality
Symptoms: The displayed pressure is off by a fixed factor or offset.
Range in the transmitter differs from the control system scaling
Check that the transmitter range and the input scaling match.
Gauge versus absolute pressure mixed up
Check the transmitter type against what the process needs.
Units changed in the transmitter
Check the configured units.
Elevation of the transmitter not compensated
Check the zero for the height difference between the tapping and the transmitter on liquid service.
Prevention: Range and units recorded in the instrument list.
Overpressure damage
Hits OEE: Availability
Symptoms: Transmitters fail after pressure spikes, such as water hammer or a blocked line.
Water hammer from fast valve closing
Check valve closing times and fit a snubber where spikes occur.
Range too low for start-up or cleaning pressures
Check the range against every operating mode.
Hydrostatic test done with the transmitter in place
Isolate or remove transmitters during pressure tests.
Thermal expansion in a blocked line
Check that trapped liquid cannot expand against the sensor.
Prevention: Failures recorded with the event that caused them.
Moisture or corrosion in the housing
Hits OEE: Availability
Symptoms: Water or corrosion is found inside the electronics housing.
Cover not closed tight after work
Close covers fully and check the O-ring.
Cable gland not sealed
Fit a gland rated for the cable and the area.
Washdown spraying directly on the housing
Use transmitters rated for washdown or shield them.
Conduit draining into the housing
Fit a drain or loop in the conduit.
Prevention: Housings inspected during planned maintenance.
Signal lost at the control system
Hits OEE: Availability
Symptoms: The control system shows a bad value or a loop fault for the transmitter.
Loop power missing
Check the loop supply and its fuse or circuit breaker.
Broken wire in the loop
Check the loop end to end with a loop calibrator; work in live panels only as an authorised person.
Input channel fault
Test the input channel by simulating a current with the calibrator.
Transmitter failed
Replace the transmitter and load its saved configuration.
Prevention: Loop faults recorded by tag number.
Differential pressure flow reading wrong
Hits OEE: Quality
Symptoms: Flow calculated from differential pressure disagrees with other measurements.
High and low sides swapped
Check the impulse line connections to the high and low ports.
Equalising valve left open
Check the manifold valve positions.
Impulse lines with different fill levels
Fill or drain both lines the same way.
Square root applied twice or not at all
Check where the square root is calculated.
Prevention: Differential pressure loops checked after any manifold work.
Guidance only. Always follow lockout/tagout and your site's safe-work procedures, and verify against OEM manuals before acting.
Related equipment guides: flow meter · control valve · PLC · hydraulic system · compressed air system · temperature sensor
Stop the same fault coming back
Recurring pressure transmitter stops usually trace to a cause you cannot see by hand. The partner we recommend is Fabrico: it tracks OEE and downtime live from PLCs, IoT sensors or AI cameras; where cameras are fitted, the video of a stop sits next to its machine data so the cause can be reviewed; and a technician opens the work order from the stop in the same system. Data is hosted in the AWS EU region, and Fabrico and the company behind it hold ISO/IEC 27001, ISO/IEC 20000-1 and ISO 9001.
Book a Fabrico demo
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Related tools: full troubleshooting directory · OEE calculator · downtime cost · MTBF / MTTR · glossary
Methods that cut recurring stops: the six big losses · root cause analysis · preventive vs predictive maintenance · TPM · SMED & changeover