C001A code meaning
Left Rear Hydraulic Release Too Long
What C001A means
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.
C001A at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor2 to 4 hours
- Clears after repairWhen cleared with a scanner
Symptoms of C001A
- ABS warning lamp on
- ABS and stability control disabled
- Extended or firm pedal during hard braking
Common causes of C001A
- Most likelyOutlet valve sticking or slow
- PossibleRestricted hydraulic path or contaminated fluid
- Less likelyPump or accumulator cannot accept fluid
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Lr ABS outlet valveHcu
What each part of C001A means
| C | Chassis system: brakes, ABS, steering and suspension. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 1A | The exact fault in that area. |
What to do next
- Note C001A and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about C001A
What does C001A mean?
C001A means "Left Rear Hydraulic Release Too Long". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with C001A?
Drive gently and only to a workshop. With C001A the car can go into limp mode (reduced power) to protect itself.
Will C001A fail an emissions test?
C001A is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is C001A to fix?
Difficulty: workshop only. A typical repair takes 2 to 4 hours of work. This is a job for a workshop.
Will C001A clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.