What does it mean?
This diagnostic trouble code (DTC) is a generic powertrain code, meaning it applies to OBD-II equipped vehicles (VW, Ford, Audi, Buick, GM, etc.). Although generic, specific repair steps may vary by make/model.
A P0318 fault code belongs to the category of codes that includes ignition system codes. The reason is that sometimes “rough road conditions” are actually an interpretation from sensors that have essentially detected the engine’s crankshaft moving unexpectedly.
The vehicle’s sensor system and PCM, or Powertrain Control Module, may indicate rough road conditions. For example, engine speed may be irregular when the vehicle is driven on very rough or off-road surfaces. This can cause the PCM to interpret it as an engine malfunction such as a misfire.
Some vehicles may have a road sensor, an accelerometer, or some may use an ABS wheel sensor and the Electronic Brake Control Module (EBCM) to help determine difficult road conditions.
Regardless of the exact system used in your vehicle, if you get this fault code, it means the PCM has detected a rough road condition that requires attention. Typically, this code is only set when the readings are identical after multiple drive cycles. This code refers to the electrical circuit of the Rough Road Sensor A.
Symptoms
Most fault codes trigger the Check Engine light (or Malfunction Indicator Lamp MIL). For this P0318 DTC, the light is not illuminated. However, you may have other warning lights on (traction control, ABS, etc.) or even experience engine misfires or rough operation.
Causes
Possible causes for setting this code include:
Faulty rough road sensor (if applicable)
Wiring/electrical fault related to sensors
The control unit needs to initialize the new road sensor
Other possible causes
Diagnostic and Repair Procedures
A good first step is to check for Technical Service Bulletins (TSBs) that may apply to your vehicle’s year/make/model. If the issue is known, there may be a specific bulletin to assist with diagnosing and repairing your exact problem. This can save you time and money.
You should obtain a vehicle-specific repair guide to help determine the exact type of rough road detection system used by your vehicle.
If you have other misfire, ABS, or related codes, you should generally address those before proceeding with repairing a P0318. Nevertheless, save all freeze frame data, as it may be useful in any diagnostics.
If your vehicle has an accelerometer sensor, check the sensor’s condition, wiring, and connectors for any issues. Repair as needed. Then use a digital volt ohmmeter (DVOM) to check continuity, resistance, and other electrical aspects according to manufacturer specifications.
If possible, use an advanced scan tool to drive the vehicle on rough roads and monitor sensor readings from the appropriate vehicle sensors to determine if you can replicate the problem, helping to pinpoint where the issue lies.