P0805
Clutch Position Sensor A Circuit.
- Generic
- Powertrain
- Generic code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 8
- AreaTransmission
- 05
- FaultThe specific fault in that area
What it means
P0805 is the generic code for a fault in the clutch position sensor 'A' circuit. The control unit monitors the signal from this sensor to know whether the clutch pedal or actuator is engaged or released. It sets the code when the signal is missing, out of range, stuck or does not make sense compared with other inputs such as vehicle speed and engine speed.
Symptoms
- Malfunction indicator lamp or gearbox warning light on
- Engine will not crank, or cranks only when the clutch pedal is pressed hard or held down
- Start-stop system not working
- Cruise control not working or cutting out
- Poor or jerky gear changes on automated manual or dual-clutch gearboxes
- Gearbox stuck in one gear or in limp mode on automated gearboxes
Possible causes
- Faulty clutch position sensor or switch, worn or out of adjustmentlikely
- Damaged, chafed or corroded wiring to the sensor, including open circuit or short to earth or supplylikely
- Poor connection at the sensor or control unit plug, such as corrosion, bent pins or loose terminalslikely
- Sensor mounting, pedal bracket or actuator mechanically loose, misaligned or damagedpossible
- Worn clutch, release mechanism or actuator causing the position reading to be implausible (mainly automated gearboxes)possible
- Low or poor supply voltage or earth fault affecting the sensor reference circuitpossible
- Faulty engine or transmission control unitrare
How to diagnose
- Read all stored codes and freeze frame data, noting whether the fault is current or intermittent, and check for other gearbox or network codes.
- Check the battery condition and charging voltage, as low voltage can cause false sensor faults.
- Visually inspect the sensor, its wiring and the plug for damage, chafing, corrosion, fluid contamination or a loose mounting.
- Using live data, watch the clutch position or switch status while pressing and releasing the pedal, and check it changes smoothly and fully through its range.
- Check the pedal or actuator for free movement and correct mechanical adjustment against the manufacturer's specification, which varies by model.
- With the sensor unplugged and ignition on, measure the supply, reference and earth at the plug against the wiring diagram.
- Check the signal wire for continuity, and for shorts to earth or supply, between the sensor and control unit.
- On automated or dual-clutch gearboxes, follow the manufacturer's procedure to assess clutch and actuator condition, as this depends on the gearbox type.
How to fix
- Repair or replace damaged wiring and clean or replace corroded or damaged connectors.
- Replace the clutch position sensor or switch if it fails testing, then adjust it to specification.
- Correct the mounting, pedal bracket or linkage fault that is affecting the sensor position.
- Repair any supply or earth fault found on the sensor circuit.
- Where the clutch or actuator is worn or faulty on an automated gearbox, repair or replace it and carry out any required adaptation or relearn procedure.
- Replace or repair the control unit only after all wiring and sensor faults are ruled out, and carry out any required programming.
Can I keep driving?
Medium severity
The car can often be driven short distances, but you may be stranded if it will not start or goes into limp mode. Get it checked soon, especially on automated gearboxes, where gear changes may be affected.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.