C004C

Brake Booster Motor A Position Sensor Exceeded Learning Limit

Moderate severity

Brake booster motor A position sensor learned offset exceeded the allowed range. Boost control tracks commanded vs. actual manifold pressure; persistent deviation means wastegate, vanes, hose or actuator are not delivering the requested pressure.

Common causes

Calibration not performed after replacement
One of the most commonly reported causes for this code — check this first.
high
Typical part cost: $90-550
See all causes + fix costs
Create a free Wrenchify account to unlock the rest for C004C.
Unlock causes
Free forever · No credit card

First things to check

1Confirm the code with a scan tool and check for additional related codes.
2Inspect the relevant sensors, wiring, and connectors for damage or corrosion.

Get the full step-by-step diagnosis

Create a free Wrenchify account to unlock the rest for C004C.

Unlock diagnosis

Free forever · No credit card

Related codes

See related trouble codes

Create a free Wrenchify account to unlock the rest for C004C.

Unlock related codes

Free forever · No credit card

Frequently asked questions

What does C004C mean?

C004C means "Brake Booster Motor A Position Sensor Exceeded Learning Limit". It is a generic OBD-II code that points to a fault in the chassis.

What are the most common causes of C004C?

calibration not performed after replacement — these are the most commonly reported causes. Verify with a proper diagnosis before replacing parts, or use the Wrenchify app for a vehicle-specific diagnosis.

Can I keep driving with this code?

The vehicle is usually drivable for short distances, but the problem can worsen or affect emissions. Diagnose and repair as soon as practical. Use the Wrenchify app for a full diagnosis specific to your vehicle.

Get the full C004C diagnosis for your vehicle

Year, make, model + step-by-step repair help — free plan included.

Diagnose C004C