What it means
The code identifies a fault involving the brake booster solenoid monitored by the brake control module. The module stores it when that solenoid or its control path fails its diagnostic checks.
How it works
The brake booster solenoid is an electrically controlled part of the booster assistance system. The brake control module monitors its circuit and operation, and stores C0022 when the solenoid or its control path fails a diagnostic check.
Common causes
Most likely first.
- Faulty brake booster solenoid
- Damaged wiring or connector
- Blown fuse or poor power supply
- Brake control module fault
Symptoms
- Brake warning light
- ABS or stability warning light
- Increased pedal effort
- Reduced brake assist
How to diagnose it
- Read brake-control codes and freeze-frame data to see whether C0022 is accompanied by power-supply or booster-performance faults.
- Inspect the booster solenoid connector and wiring for loose pins, corrosion, chafing, or damage.
- Check the relevant fuse and power supply using the vehicle’s wiring information.
- Test the solenoid circuit for continuity and shorts according to the manufacturer’s procedure.
- If power, ground, and wiring are correct, test the solenoid coil and commanded operation.
- Consider a brake control module fault only after the solenoid and its circuit pass their checks.
Common fixes
- Secure or clean the booster-solenoid connector and repair damaged wiring.
- Replace a blown fuse after checking for the cause of the failure.
- Restore a poor power or ground connection.
- Replace the faulty brake booster solenoid if testing confirms it.
- Repair the brake control module if its output is faulty after the solenoid circuit is verified.
Can I keep driving?
Brake assist may be reduced, which can increase pedal effort and stopping distance. Avoid driving if the pedal becomes hard or braking feels weak, and have the fault checked promptly.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.