Chassis, generic

C055F BSCM/EBBC Hydraulic Unit Performance

Check engine lightOn
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

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.

Likely causes

Internal leak or failure of the master cylinder or pedal simulator
Low battery voltage, especially in severe cold, during the self-test
Brake module software flagging the unit too readily (update available)
Poor power or ground terminals at the brake module

Symptoms

  • Service Brake System message, ABS and stability lamps
  • Hard pedal or changed brake pedal effort
  • Check-engine lamp on some models

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€80–2,500
Time0.3–4 h

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

Parts involved

bscm hydraulic unitbrake system control module

Related codes

C055DC055EC0597C053DC0563

References: static.nhtsa.gov, static.nhtsa.gov, static.nhtsa.gov, gsi.ext.gm.com.