P0858: Traction Control Input Signal Low
What to do
Either the car feels down on power for no reason, or traction control has switched itself off. Both come from the same circuit fault, and which one you get depends on how the vehicle is wired.
What this code means
The traction control request circuit reads below its valid range, normally a short to ground. Depending on how the signal is arranged this is read either as a permanent request for torque reduction — the gutless-car case described under P0856 — or as no valid request at all, in which case traction control withdraws.
Likely causes
Start here
- Wiring shorted to ground · moderate
Less common
- Faulty stability control module · specialist
- Corroded or loose connector · easy
- Poor module ground connection · moderate
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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