Cause
Blocked or restricted brake hydraulic passage
A brake circuit that will not let fluid move freely — most often inside the ABS modulator, where the passages are a fraction of a millimetre across.
The symptom that matters is a brake slow to release rather than slow to apply. Pressure gets to the wheel and then cannot get out, so the brake drags: that corner heats up, the car pulls to one side, and the pad and disc on that wheel wear far faster than their opposite numbers.
Old brake fluid is the usual reason, because the corrosion and debris it carries end up wherever the passages are narrowest.
A collapsed flexible hose imitates it exactly and is much cheaper. The inner lining can lift and act as a one-way valve — fluid in, none out. The test that separates them is simple: crack the bleed nipple at the dragging caliper. If the brake releases instantly, the restriction is upstream in the hose or modulator, and the caliper is innocent.
Check the cheap thing first. A hose is an hour; a modulator is not.
Typically specialist work. Needs equipment or training most home workshops do not have.
Some of these codes mean you should stop driving
4 of the 4 codes this can cause indicate a fault where continuing to drive risks damage or is unsafe. Which one you have matters more than the cause does — read the code's own page before deciding.
Codes this can cause (4)
Codes where this is a likely explanation first, rather than merely a possible one.
- C0012 Left Front Hydraulic Release Too Long Likely for this code Stop driving High
- C0016 Right Front Hydraulic Release Too Long Likely for this code Stop driving High
- C001A Left Rear Hydraulic Release Too Long Likely for this code Stop driving High
- C001E Right Rear Hydraulic Release Too Long Likely for this code Stop driving High
Information, not instruction
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