Rough Road Sensor A Signal Circuit
What does P0318 mean?
The P0318 code means the vehicle's onboard diagnostic system has detected: Rough Road Sensor A Signal Circuit. This is a low severity code.
Common Symptoms
- Check Engine Light illuminated
- False misfire codes stored during rough road driving
- No noticeable drivability issues
- ABS or traction control warning light may be on
- Intermittent misfire detection on uneven surfaces
Probable Causes (Ranked by Likelihood)
- Faulty rough road sensor or wheel speed sensor Very High
- Damaged wiring to rough road or wheel speed sensor High
- Corroded sensor connector High
- ABS module communication fault Moderate
- PCM calibration issue Low
Step-by-Step Diagnostic Procedure
-
Read all stored codes -- look for ABS or wheel speed sensor codes that accompany P0318
-
Inspect wheel speed sensor connectors at all four wheels for corrosion or damage
-
Test wheel speed sensor output using a multimeter -- should produce AC voltage when the wheel is spun
-
Check wiring from wheel speed sensors to the ABS module for breaks or shorts
-
Verify the ABS module is sending rough road data to the PCM using a bidirectional scan tool
Frequently Asked Questions
Can I drive with code P0318?
Yes. This code does not affect engine performance directly. The main consequence is that the PCM may falsely detect misfires when driving on rough or bumpy roads.
What is the difference between P0317 and P0318?
P0317 means the rough road hardware is missing or not detected at all. P0318 means the hardware is present but its signal circuit has a fault, such as a bad sensor or wiring issue.
Can a bad wheel bearing cause P0318?
Indirectly, yes. A severely worn wheel bearing can affect the wheel speed sensor signal quality, as the sensor may no longer maintain the correct air gap to the tone ring.