Chassis, generic

C055E Brake Hydraulic Circuit A Leak

Check engine lightOn
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

C055E reports a leak in hydraulic circuit A, the counterpart of C055D. Land Rover documents it on the Defender L663 from 2020 as C055E-7A, meaning lost fluid or a failed seal, with amber ABS and DSC lamps. By design the code survives a simple clear: after the repair the ignition is cycled until the car sleeps, switched on again, left 15 s without touching the pedal, then the pedal is held firmly for up to 120 s while the valves click through a self-check (SSM 74988). If lamps stay lit, the leak is still there. GM's 2025 EBCM tables list C055E for the second circuit with the same leakage limits as C055D and Type A MIL. Driving on is risky, because only one circuit may be braking.

Likely causes

Fluid escaping from a line, hose, union or caliper of circuit A
Internal seal failure in master cylinder or hydraulic unit
Repair done but the required self-check was not completed, so the code stays
Air trapped after bleeding or component replacement

Symptoms

  • Amber ABS and DSC/ESC lamps, possibly red brake warning
  • Longer pedal travel or spongy feel
  • Warning returns after clearing until the self-check passes

Repair estimate

DifficultyHardWorkshop job
Parts and labour€60–2,500
Time0.5–4 h

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

Parts involved

brake circuit aabs hydraulic unit

Related codes

C055DC055FC05B0C05B1

References: static.nhtsa.gov, gsi.ext.gm.com, law.cornell.edu.