Chassis, generic

C001A Left Rear Hydraulic Release Too Long

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

Set when the ABS modulator cannot release pressure at the left rear wheel within the expected time during a control cycle, the left rear equivalent of C0012 and C0016. After the module commands the left rear outlet valve to dump pressure it expects wheel speed to recover and line pressure to fall; a release that exceeds the calibrated time limit indicates a sticking valve, a restricted hydraulic path or an accumulator or pump unable to accept fluid. ABS and stability control are disabled and the ABS warning lamp is set. No manufacturer documents this code publicly; NHTSA's study covers the release step of the ABS cycle, and a patent shows how a full low-pressure accumulator slows it.

Likely causes

Outlet valve sticking or slow
Restricted hydraulic path or contaminated fluid
Pump or accumulator cannot accept fluid

Symptoms

  • ABS warning lamp on
  • ABS and stability control disabled
  • Extended or firm pedal during hard braking

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€300–1,800
Time2–4 h

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

Parts involved

lr abs outlet valvehcu

Related codes

C0018C0019C001E

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