Traction Control Input Signal Range/Performance
Code P0857 indicates that the Powertrain Control Module (PCM) has detected a signal from the traction control system that is out of the expected range or not performing correctly. This typically involves the brake switch, wheel speed sensors, or the steering angle sensor. The PCM uses this input to modulate engine power and braking to maintain traction. A faulty signal can cause the traction control system to malfunction, potentially activating the warning light and affecting vehicle stability.
01. Most Common Causes
- Faulty brake switch or misadjusted brake pedal position sensor
- Wheel speed sensor malfunction or wiring issues
- Steering angle sensor calibration error or failure
- Corroded or damaged connectors in the traction control circuit
02. Symptoms You Will Notice
- Traction control warning light illuminated on dashboard
- Traction control system inoperative or engaging unexpectedly
- ABS light may also be on
- Reduced engine power or limp mode activation
03. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm code P0857 and check for additional related codes.
Step 2: Inspect brake switch operation and adjust or replace if faulty.
Step 3: Check wheel speed sensors for damage, debris, or wiring issues; test resistance and signal output.
Step 4: Verify steering angle sensor calibration using a scan tool; recalibrate if necessary.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is generally not recommended to drive with this code as the traction control system may not function properly, increasing the risk of loss of vehicle control, especially in slippery conditions.
How much does it cost to fix?▼
The cost to fix P0857 typically ranges from $50 to $150 for diagnosis and simple repairs like brake switch replacement, but can be higher if wheel speed sensors or steering angle sensor replacement is needed.