C055FBSCM/EBBC Hydraulic Unit Performance
- Generic OBD-II code · Chassis
- Turns on the check-engine light
- Can trigger limp mode
- How the car detects it
- The brake system control module (BSCM) or electronic brake boost controller (EBBC) has found that its hydraulic unit – master cylinder, pedal simulator, separation valves or boost plunger – does not perform as calculated. GM's 2019 tables test it during shutdown: a simulator leak sets C055F if secondary pressure drops under 15 bar; in 2025 a master cylinder leakage above 200 mm³/s also counts, Type A with MIL. On 2026 Silverado/Sierra 1500 GM replaces the master cylinder (PIT6450A); on 2022–26 trucks and SUVs the code appeared below −23 °C from low battery voltage (PIT6476). Jeep logs it as ABS Hydraulic Unit Performance on the 2021 Wrangler 4xe with MIL and fixes stored cases by ABS software (08-032-22). Expect a hard or changed pedal.
- What you may notice
- Service Brake System message, ABS and stability lamps
- Hard pedal or changed brake pedal effort
- Check-engine lamp on some models
- Likely causes
- LikelyInternal leak or failure of the master cylinder or pedal simulator
- PossibleLow battery voltage, especially in severe cold, during the self-test
- PossibleBrake module software flagging the unit too readily (update available)
- RarePoor power or ground terminals at the brake module
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €80 – €2,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.