P0318: Rough Road Sensor A Signal Circuit Malfunction
The P0318 code indicates a problem with the rough road sensor (also known as the accelerometer or road surface sensor) circuit. This sensor detects vibrations and bumps to help the engine control module (ECM) adjust ignition timing and fuel delivery to prevent misfires. A faulty sensor, wiring issues, or a damaged ECM can trigger this code, often leading to drivability concerns.
01. Most Common Causes
- Faulty rough road sensor
- Damaged or corroded wiring/connectors in the sensor circuit
- Poor electrical connection
- Faulty engine control module (ECM)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Engine misfire or rough idle
- Reduced fuel economy
- Hesitation or stumbling during acceleration
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 rough road sensor and its wiring for damage, corrosion, or loose connections.
Step 3: Test the sensor's voltage and resistance with a multimeter per manufacturer specifications.
Step 4: If sensor and wiring are okay, check for ECM issues or perform a relearn procedure.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as the code can cause engine misfires and reduced performance, potentially leading to further damage.
How much does it cost to fix?▼
Repair costs typically range from $50 to $150 for sensor replacement, but could be higher if wiring or ECM repairs are needed.