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DTC codes / P08xx · Transmission / P08B6

P08B6Clutch Pedal Position Sensor B Circuit Low

P08B6 means the clutch pedal position sensor B circuit is reporting a voltage lower than the manufacturer's expected range, so the engine computer cannot trust the clutch pedal's position. The computer has detected a low-voltage condition on the signal or reference circuit for sensor B, which is often the second of two redundant clutch pedal sensors used for starting, cruise control, and drivability logic.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaTransmission

Symptoms you may notice

  • The check engine light or a clutch-related warning light is illuminated on the dashboard.
  • The engine may not crank or start because the clutch pedal position is not recognized as depressed.
  • Cruise control may be inoperative or may disengage unexpectedly while driving.
  • The engine may hesitate, stumble, or exhibit poor drivability during clutch engagement and gear changes.
  • A remote start system may fail to operate because the clutch safety logic is not satisfied.
  • Often no symptoms besides the warning light, especially if sensor A still provides a valid signal.

Common causes, most likely first

  1. A faulty clutch pedal position sensor B that has failed internally and is pulling the signal voltage low.
  2. Damaged, chafed, or corroded wiring in the sensor B signal or reference circuit, often near the pedal assembly.
  3. A poor electrical connection at the sensor B connector, including backed-out terminals or water intrusion.
  4. A short to ground on the sensor B signal wire where it rubs against a metal bracket or pedal box component.
  5. A misadjusted or improperly installed clutch pedal position sensor B after recent clutch or pedal work.
  6. A failing clutch pedal assembly or return spring that prevents the sensor from sweeping its full range.
  7. Rarely, a fault in the engine control module or its reference voltage supply affecting multiple sensors.

How to diagnose and fix it

  1. Connect a scan tool and read the clutch pedal position sensor B voltage and percentage while slowly pressing and releasing the clutch pedal to confirm the low signal.
  2. Visually inspect the sensor B connector and harness for corrosion, chafing, loose terminals, or signs of water intrusion, and repair as needed.
  3. Check the sensor B reference voltage and ground at the connector with a digital multimeter to rule out a supply or ground fault before condemning the sensor.
  4. Perform a wiggle test on the sensor B harness while watching live data to catch intermittent opens or shorts that appear only under vibration.
  5. Verify the clutch pedal mechanical operation and sensor B adjustment, and reinstall or recalibrate the sensor according to the manufacturer's procedure if it was recently disturbed.
  6. If the circuit checks good and the signal remains low through the sensor's full travel, replace clutch pedal position sensor B and clear the code.
  7. After repair, clear the diagnostic trouble codes and perform a road test with cruise control and start-stop operation to confirm the code does not return.

Clutch sensor B low-voltage traps to avoid

  • Many vehicles use two clutch pedal position sensors for redundancy, and a low code on sensor B often does not disable the vehicle because sensor A still allows starting and driving, which is why drivers delay diagnosis.
  • A common misdiagnosis is replacing sensor B when the real fault is a chafed signal wire near the clutch pedal bracket, so always perform a loaded voltage drop test on the signal circuit before installing parts.
  • Aftermarket floor mats, pedal covers, or clutch pedal stop brackets can prevent full pedal travel and cause the sensor B signal to stay low, mimicking an electrical failure.
  • A weak or failing battery can cause reference voltage to sag on some vehicles, setting a low circuit code for sensor B even though the sensor itself is healthy.
  • The code can be set by a short to ground in a shared sensor return circuit that affects other pedals or switches, so check for companion codes before chasing sensor B alone.

Can I keep driving with P08B6?

The vehicle is usually safe to drive if it starts and shifts normally, but avoid relying on cruise control and be aware that the clutch safety start function may be compromised. If the engine will not crank or the clutch pedal feels abnormal, stop driving and have the circuit diagnosed promptly.

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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