P087B
Clutch Position Sensor B Circuit Range/Performance.
- Generic
- Powertrain
- Generic code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 8
- AreaTransmission
- 7B
- FaultThe specific fault in that area
What it means
P087B is the generic code for a range or performance fault in the clutch position sensor 'B' circuit. The control unit sees a signal from this sensor that is implausible, either out of the expected range or not matching the clutch actuator command or related inputs such as the other clutch position sensor, pedal position or engine and gearbox speed. Which transmission the sensor belongs to (manual with clutch pedal sensing, automated manual or dual-clutch) and where 'B' sits depends on the model and the manufacturer's definition.
Symptoms
- Warning light on, possibly with a transmission or gearbox fault message
- Difficulty starting, or the car refusing to start because the clutch signal is not recognised
- Jerky, slipping or harsh gear changes on automated or dual-clutch gearboxes
- Cruise control, stop-start or hill-hold not working
- Transmission going into a limp-home mode or stuck in one gear
- Engine stalling or hesitating when pulling away
Possible causes
- Faulty clutch position sensor, or a sensor out of adjustmentlikely
- Damaged wiring, poor connector contact or corrosion in the sensor circuitlikely
- Worn clutch, clutch actuator or release mechanism giving a position that does not match the expected rangepossible
- Sensor reference voltage or earth fault, for example from a low battery or poor earth connectionpossible
- Contamination or debris on the sensor or its target, or a mechanical fault in the pedal assemblypossible
- Faulty control unit or outdated software calibration (only where the manufacturer lists it as a known cause)rare
How to diagnose
- Read all stored and pending codes and the freeze frame data, and note any other clutch, gearbox or speed sensor codes
- Check the battery condition and charging voltage, since low voltage can cause false sensor faults
- Inspect the sensor, wiring and connectors for damage, chafing, water ingress, corrosion and loose pins
- Check the sensor mounting and its mechanical linkage or target for looseness, damage or contamination
- Using live data, watch the clutch position value while operating the pedal or actuator and look for dropouts, jumps or values that do not move smoothly
- Check the sensor supply voltage, signal and earth against the manufacturer's specification, and test wiring for continuity and shorts
- Compare with the other clutch position sensor, if fitted, and check the clutch and actuator for wear or sticking
- Check for applicable service bulletins or software updates for the model before replacing the control unit
How to fix
- Repair or replace damaged wiring, and clean or replace faulty connectors
- Replace the clutch position sensor and adjust or relearn it as the manufacturer specifies
- Repair or replace a worn clutch, actuator or release mechanism if it is causing the out-of-range reading
- Correct battery, supply or earth faults
- Clean contamination and repair any mechanical fault in the pedal or sensor mounting
- Update the control unit software if an outdated calibration is a known cause for that model, then clear the code and road test
Can I keep driving?
The car may be driveable, but gear changes or starting can become unreliable and the gearbox may go into limp mode. Get it checked soon and avoid long journeys, as the fault could leave you stranded or damage the clutch.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.