Clutch Position Sensor Circuit
Diagnostic trouble code P0805 indicates that the powertrain or transmission control module has detected an electrical malfunction in the clutch position sensor circuit. The module sets this code when the voltage signals from the sensor do not match the expected values based on current operating conditions or pedal movement.
This code should be addressed soon because it can prevent the vehicle from starting due to the starter safety interlock system. While not inherently dangerous while driving, it can leave you stranded if the computer cannot verify the clutch pedal is depressed.
Common symptoms
- Illuminated Check Engine Light
- Engine will not crank or start
- Cruise control system is inoperative
- Harsh or erratic shifting (in vehicles with automated manual transmissions)
- Engine stalling or surging when the clutch is engaged or disengaged
Likely causes
- Defective clutch position sensor
- Damaged, corroded, or loose wiring and connectors in the sensor circuit
- Misadjusted clutch position sensor or switch
- Mechanical wear or damage to the clutch pedal assembly
- Faulty Powertrain Control Module (PCM) or Transmission Control Module (TCM)
What to check before replacing parts
Visually inspect the clutch position sensor, wiring, and connectors under the dashboard.
Look for: Look for disconnected plugs, chafed wires, or physical damage to the sensor mounting that could cause an open or short circuit.
Connect a scan tool and monitor the clutch position sensor PID while pressing the pedal.
Look for: The data should show a smooth transition in voltage or percentage as the pedal is depressed and released; erratic or static readings indicate a sensor or circuit fault.
Verify the mechanical adjustment and mounting of the clutch position sensor.
Look for: Ensure the sensor is securely mounted and properly contacts the clutch pedal arm throughout its full range of motion.
Test the sensor's reference voltage and ground circuits with a digital multimeter.
Look for: You should see a steady 5-volt reference signal and a solid ground; missing voltage indicates a wiring issue back to the PCM.
Perform a continuity and resistance test on the signal wire between the sensor and the PCM.
Look for: High resistance or an open circuit (infinite ohms) indicates a broken wire that needs to be repaired or replaced.
This page explains the generic P0805 definition and is general reference information, not a diagnosis for your specific vehicle. Actual causes, severity, and repairs vary by make, model, engine, and mileage — always confirm with a scan tool and a qualified technician before replacing parts.
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