Clutch pedal position sensor signal circuit open, shorted, or high resistance; Faulty clutch pedal position sensor or its internal potentiometer; Clutch pedal binding, incorrect free play, or a misadjusted pedal stop; Low or contaminated brake/clutch fluid affecting clutch actuation; Air trapped in the clutch hydraulic circuit preventing full pedal travel; Worn clutch disc or pressure plate changing the pedal's effective range; Transmission control module software needing an update or a failed relearn due to battery voltage issues

DTC codes / P08xx · Transmission / P08AC

P08ACClutch Pedal Position Not Learned

Q: What does code P08AC mean?

Clutch Pedal Position Not Learned. P08AC means the transmission control module has not successfully learned the clutch pedal's fully released and fully applied positions, so it cannot reliably coordinate clutch operation with engine torque. The computer detects this when the learned position values are missing, out of range, or invalid after a relearn attempt.

P08AC means the transmission control module has not successfully learned the clutch pedal's fully released and fully applied positions, so it cannot reliably coordinate clutch operation with engine torque. The computer detects this when the learned position values are missing, out of range, or invalid after a relearn attempt.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaTransmission

Symptoms you may notice

Illuminated check engine light or transmission warning light, often with no other symptoms
Harsh or jerky clutch engagement when pulling away from a stop
Difficulty shifting gears or a clutch that feels inconsistent
Engine stalling or flaring when the clutch is operated
Transmission refusing to enter certain gears or dropping into limp mode
A relearn procedure that fails to complete or repeatedly aborts

Common causes, most likely first

Clutch pedal position sensor signal circuit open, shorted, or high resistance
Faulty clutch pedal position sensor or its internal potentiometer
Clutch pedal binding, incorrect free play, or a misadjusted pedal stop
Low or contaminated brake/clutch fluid affecting clutch actuation
Air trapped in the clutch hydraulic circuit preventing full pedal travel
Worn clutch disc or pressure plate changing the pedal's effective range
Transmission control module software needing an update or a failed relearn due to battery voltage issues

How to diagnose and fix it

Verify battery voltage and charge it if low, since a failed relearn often results from weak voltage during the procedure
Scan all modules for related codes and check clutch pedal position sensor live data through the full pedal travel
Inspect the clutch pedal position sensor connector and wiring for corrosion, chafing, or loose pins
Check clutch pedal mechanical operation for binding, correct free play, and full travel to the stop
Bleed the clutch hydraulic circuit and verify fluid level and condition
Perform the manufacturer's clutch pedal position relearn procedure exactly as specified, including any required driving cycle
If relearn still fails, replace the clutch pedal position sensor and repeat the relearn before condemning the transmission control module

Why the clutch relearn keeps failing

A weak or failing battery is one of the most common reasons a clutch pedal relearn aborts, even when the engine starts normally.
Aftermarket floor mats or a pedal stop bracket can prevent the pedal from reaching the full-travel point the module needs to learn.
A clutch pedal position sensor can produce plausible live data at rest yet drop out only at the extreme ends of travel, so sweep the pedal slowly while watching the scan tool.
This code does not automatically mean the sensor is bad; a worn clutch or air in the hydraulic line changes pedal geometry enough to make learning impossible.
Some vehicles require the relearn to be performed with the transmission at operating temperature and on level ground, and skipping that step causes repeat failures.

Can I keep driving with P08AC?

The vehicle is usually drivable, but clutch engagement may be harsh or inconsistent, so avoid aggressive launches and stop-and-go traffic until the relearn is completed. If the clutch slips, the engine flares, or the transmission drops into limp mode, park the vehicle and arrange diagnosis rather than continuing to drive.

Tools that help

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