Chassis, generic

C0022 Brake Booster Solenoid

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

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.

Likely causes

Solenoid coil open or shorted
Corroded connector or chafed wiring
Internal booster assembly fault

Symptoms

  • Changed brake pedal effort or feel
  • Noise from the brake system
  • ABS or brake warning lamp on

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€250–1,800
Time1–4 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

brake booster solenoid

Related codes

C0021C0047C0048

References: patents.google.com, rosap.ntl.bts.gov, en.wikipedia.org.