P0857Traction Control Input Signal Range/Performance
- Generic OBD-II code · Powertrain
- How the car detects it
- The traction control input carries the request of the ABS/stability module to the engine module to cut torque when wheels spin. Older cars used a wire with a voltage or duty-cycle signal, hence the low and high variants; today it is a CAN message, where pure loss of communication sets U0121 or U0415 instead. California's OBD rule counts traction control as a safety-only system that may be exempted, so these codes normally carry no MIL. P0857 means the signal is electrically valid but does not fit the driving state, such as a request without wheel slip or switching too often. No maker documents the code; GM covers such checks under P0856. The receiving module ignores the request and traction control is disabled.
- What you may notice
- Traction or stability control lamp on, system switched off
- Traction control intervenes unexpectedly or not at all
- Engine power briefly reduced
- Likely causes
- PossibleSoftware or calibration of brake or engine module
- PossibleLoose contact or corrosion between brake module and engine module
- PossibleWheel speed fault in the ABS causing false slip detection
- RareBrake module faulty
- Repair
- Medium · Usually a job for a workshop.Typical cost: €80 – €1,200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.