Rough Road Sensor A Signal Circuit
What it means
P0318 means the ECM has a problem with the "A" rough-road sensor signal. This sensor tells the engine computer when you're driving over bumps so it doesn't mistake road-induced crankshaft speed changes for an engine misfire. The car drives normally, but the misfire diagnostic may be paused until the circuit is repaired.
Can I keep driving? The car itself drives normally — this is an input-circuit fault — but the ECM may suspend the misfire monitor, so it's worth fixing so a real misfire isn't missed.
Real-world scan data
Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.
Common symptoms
What you'll notice
- Check-engine light on
- Often no noticeable change in how the car drives
- Misfire monitor may not complete (readiness not set)
- Related crankshaft/misfire codes may appear alongside it
Common causes
Most likely first
- Faulty rough-road sensor (or the G-sensor/wheel-speed source it uses)Likely
- Open, shorted, or damaged wiring in the signal circuitCommon
- Loose or corroded connector at the sensor or moduleCommon
- Loss of rough-road data over the vehicle network from the ABS moduleLess often
How to diagnose & fix
Work through it in order
- Scan for other stored codes first — network or ABS faults can trigger this.
- Inspect the rough-road sensor connector and wiring for damage or corrosion.
- Check the signal circuit for continuity and correct reference voltage.
- Confirm the ABS/data source is reporting rough-road information correctly.
- Replace the sensor only after wiring and data-source checks pass. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P0318?+
Can I just clear P0318?+
Related codes
Read & clear P0318 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.