Traction Control Input Signal Low
The P0858 code indicates that the Powertrain Control Module (PCM) has detected a low voltage signal from the traction control system input circuit. This typically occurs when the signal from the wheel speed sensors or the traction control module is below the expected threshold, often due to a faulty sensor, damaged wiring, or a poor electrical connection. The PCM uses this input to manage traction control and stability systems, so a low signal can disable these features and potentially affect engine performance.
01. Most Common Causes
- Faulty wheel speed sensor
- Damaged or corroded wiring/connectors in the traction control circuit
- Malfunctioning traction control module
- Low battery voltage or charging system issue
02. Symptoms You Will Notice
- Traction control warning light illuminated
- Check Engine Light on
- Traction control system inoperative or disabled
- Possible reduced engine power or limp mode
03. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm the code and check for additional codes.
Step 2: Visually inspect the wiring and connectors related to the traction control input circuit for damage, corrosion, or loose connections.
Step 3: Test the wheel speed sensors and their circuits using a multimeter to check for proper resistance and voltage signals.
Step 4: If sensors and wiring are okay, test the traction control module and PCM for proper operation.
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 active, as the traction control system may be disabled, increasing the risk of loss of vehicle control in slippery conditions. Additionally, the vehicle may enter limp mode, limiting speed and performance.
How much does it cost to fix?▼
The cost to fix P0858 typically ranges from $50 to $150, depending on the cause. Replacing a wheel speed sensor can cost $50-$100, while wiring repairs may be $50-$150. Diagnostic fees may add $50-$100.