P0857 code meaning
Traction Control Input Signal Range/Performance
What P0857 means
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.
P0857 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0857
- Traction or stability control lamp on, system switched off
- Traction control intervenes unexpectedly or not at all
- Engine power briefly reduced
Common causes of P0857
- 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
- Less likelyBrake module faulty
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
ABS control moduleEngine control moduleSerial data lineSensor wiring
What each part of P0857 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 8 | Area: transmission. |
| 57 | The exact fault in that area. |
What to do next
- Note P0857 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 P0857
What does P0857 mean?
P0857 means "Traction Control Input Signal Range/Performance". The traction control input carries the request of the ABS/stability module to the engine module to cut torque when wheels spin. It is a generic code, so it means the same on every make.
Is it safe to drive with P0857?
P0857 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will P0857 fail an emissions test?
P0857 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 P0857 to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will P0857 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.