P0857: Traction Control Input Signal Range/Performance
What to do
If traction control activates on dry roads for no apparent reason, that is this fault rather than an over-sensitive system. A wheel speed sensor is the usual cause, and note whether it happens at a particular speed or on a particular kind of corner.
What this code means
The traction control request is present but implausible — a torque reduction asked for when no wheel is slipping, or a request that does not correspond to any condition the other modules can see.
A wheel speed sensor reporting incorrectly is the usual reason, and it produces a distinctive complaint: traction control intervening on dry roads at steady speed, cutting power for no reason the driver can perceive. The stability system is behaving correctly on information that is wrong, which is why the fault is rarely found by examining the stability system.
Likely causes
Start here
- Faulty wheel speed sensor · moderate
- Mismatched or incorrectly sized tyres · easy
Less common
- Faulty stability control module · specialist
- Damaged data bus wiring · specialist
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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