What causes fault code P0318?

• Most likely: Corrosion or damaged pins in the ABS control module connector • Likely: Faulty ABS control module or wheel speed sensor • Possible: Defective accelerometer/G-sensor (common on specific models like Subaru/Chrysler) • Rare: Wiring fault (open or short circuit) in the CAN-bus lines between ABS and ECU

How do you fix fault code P0318?

STEP 1: Scan for related ABS/ESC codes. P0318 is usually a secondary code triggered by an ABS fault. Check wheel speed sensor data. STEP 2: Inspect the ABS module connector for corrosion. Clean with contact cleaner if necessary. Measure CAN-bus resistance (should be approx 60 Ohms across the network with ignition off). STEP 3: Check the G-sensor/accelerometer (if equipped) using live data. It should read 1.0G at standstill or specific center-voltage (e.g., 2.5V). STEP 4: If the ABS module or sensor is confirmed faulty, replace and perform any necessary coding/calibration using a factory scan tool.

Powertrain (Engine & Gearbox)Standard EOBD

P0318 - Rough Road Sensor 'A' Signal Circuit

Q: What are the symptoms of fault code P0318?

• Check engine light (MIL) illuminated • Traction control (TCS/ESP) light may be on • ABS light may be on • No direct driveability issues, but misfire monitoring is hampered • May fail state emissions inspection due to MIL

Last updated:1 February 2026

Related:ABS Control Unit, Hjulhastighetssensor, Accelerometer (G-sensor), Wiring Harness, Engine Control Unit (ECU)

System

Powertrain (Engine & Gearbox)

Related Fault Codes

P0300

Random or Multiple Cylinder Misfire Detected

P0301

Cylinder 1 Misfire Detected

P0302

Cylinder 2 Misfire Detected

P0303

Cylinder 3 Misfire Detected

Technical Description

The P0318 code is stored when the Engine Control Module (ECM) detects an issue with the signal from the rough road sensor or the ABS control module. The OBD-II system uses this data to distinguish between actual engine misfires and crankshaft speed fluctuations caused by driving on uneven surfaces. If the ECM cannot receive a valid signal regarding road conditions, it cannot accurately perform misfire monitoring. This data is typically transmitted via the CAN-bus from the ABS/ESC module using wheel speed sensor data or a dedicated accelerometer.

Possible Causes

Corrosion or damaged pins in the ABS control module connector

Faulty ABS control module or wheel speed sensor

Defective accelerometer/G-sensor (common on specific models like Subaru/Chrysler)

Wiring fault (open or short circuit) in the CAN-bus lines between ABS and ECU

Symptoms

Check engine light (MIL) illuminated

Traction control (TCS/ESP) light may be on

ABS light may be on

No direct driveability issues, but misfire monitoring is hampered

May fail state emissions inspection due to MIL

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P0318 - Rough Road Sensor 'A' Signal Circuit

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P0318 - Rough Road Sensor 'A' Signal Circuit

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