C0022Brake Booster Solenoid
- Generic OBD-II code · Chassis
- Can trigger limp mode
- How the car detects it
- C0022 covers the solenoid valve of an electronically controllable brake booster. Patent literature shows a vacuum booster that works in two ways: by the driver's pedal in normal braking, and through a solenoid valve that changes the pressure in an auxiliary chamber so the booster applies the brakes without the pedal. NHTSA's brake study describes the conventional vacuum booster, which this valve extends, sitting ahead of the master cylinder. The module checks the coil circuit for opens, shorts and resistance out of range and whether assist follows the command. A fault removes automatic braking and can change pedal effort; the brake or ABS lamp lights. No manufacturer documents this code publicly with a retrievable bulletin.
- What you may notice
- Changed brake pedal effort or feel
- Noise from the brake system
- ABS or brake warning lamp on
- Likely causes
- LikelySolenoid coil open or shorted
- PossibleCorroded connector or chafed wiring
- RareInternal booster assembly fault
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €250 – €1,800
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.