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DTC codes / P08xx · Transmission / P08AA

P08AAClutch Pedal Position Sensor A Circuit High

P08AA indicates that the powertrain control module (PCM) has detected a high voltage condition on the signal circuit for clutch pedal position sensor A, which typically means the circuit is open, shorted to voltage, or the sensor's internal resistance has risen abnormally. The PCM expects the sensor's signal voltage to stay within a calibrated range as the clutch pedal moves, and a sustained high reading falls outside that range.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaTransmission

Symptoms you may notice

  • Illumination of the check engine light, often with no other noticeable symptoms.
  • Difficulty starting the engine because the clutch pedal must be depressed to enable the starter, and the PCM may not recognize the pedal position.
  • Inconsistent or failed engagement of cruise control, which relies on the clutch pedal signal to disengage.
  • Rough or delayed gear changes on vehicles with an automated manual or dual-clutch transmission that uses the clutch pedal signal.
  • A stored code in the transmission control module (TCM) or body control module (BCM) that shares the clutch pedal signal.
  • In rare cases, the engine may stall or hesitate when the clutch pedal is pressed due to incorrect fuel or ignition scheduling.

Common causes, most likely first

  1. An open or high-resistance connection in the signal wire between clutch pedal position sensor A and the PCM.
  2. A short to voltage on the signal circuit, often caused by chafed wiring near the pedal assembly or a pinched harness.
  3. A faulty clutch pedal position sensor A, typically due to internal wear or contamination of the potentiometer or Hall-effect element.
  4. Corroded or loose terminals at the sensor connector or at the PCM connector.
  5. A poor ground connection for the sensor, which can cause the signal voltage to float high.
  6. A misadjusted or improperly installed sensor after clutch pedal or transmission work.
  7. A rare internal PCM fault on the sensor input circuit.

How to diagnose and fix it

  1. Connect a scan tool and verify the clutch pedal position sensor A voltage reading while slowly pressing and releasing the pedal, looking for a smooth sweep without dropouts or spikes.
  2. Visually inspect the sensor connector and the wiring harness for damage, corrosion, or loose pins, and repair any obvious faults.
  3. Measure resistance or voltage on the signal circuit between the sensor and the PCM, and compare with the manufacturer's specification to confirm an open or short.
  4. Check the sensor's ground circuit for excessive resistance using a voltage drop test under load.
  5. If the wiring and grounds are good, replace clutch pedal position sensor A with a quality part and clear the code.
  6. After repair, perform a relearn or calibration procedure if required by the vehicle manufacturer, then test-drive to confirm the code does not return.
  7. If the code persists after all external checks, diagnose the PCM input circuit or substitute a known-good PCM for testing.

Clutch Pedal Sensor High Voltage Traps

  • A high voltage reading on the signal circuit often results from an open circuit rather than a failed sensor, so resistance testing of the wiring is more reliable than condemning the sensor first.
  • The clutch pedal position sensor shares its signal with the engine start system and cruise control, so a no-crank condition or inoperative cruise control can be the first clue before the code is even set.
  • Aftermarket floor mats or pedal covers that restrict pedal travel can cause the sensor to report an implausible high voltage at the top of its range, mimicking an electrical fault.
  • On some vehicles, the clutch pedal position sensor is integrated into the clutch master cylinder pushrod, and a worn pushrod bushing can hold the sensor at an extreme position and set this code.
  • A weak or failing battery can cause the PCM to log a high voltage fault on the sensor circuit during cranking if system voltage drops and the reference voltage becomes unstable.

Can I keep driving with P08AA?

You can usually drive the vehicle, but the engine may not start reliably because the clutch pedal signal is needed for starter enable, and cruise control may be disabled. Avoid long trips and have the fault diagnosed soon, especially if the engine has failed to crank or the transmission shifts abnormally.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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