Technical Description of OBD-II Trouble Code
Signal Circuit for Rough Road Sensor A
What does that signify?
This diagnostic trouble code (DTC) is a generic powertrain code that is applicable to OBD-II equipped vehicles (VW, Ford, Audi, Buick, GM, etc.). Although it is a generic code, the specific repair steps may vary depending on the make and model of the vehicle.
A P0318 trouble code falls under the category of codes that include ignition system codes. This is because sometimes the “rough road hardware” is actually an interpretation from sensors that have detected unexpected movement of the engine’s crankshaft.
The system of sensors and the vehicle’s PCM, or powertrain control module, can indicate rough terrain conditions. For instance, when the vehicle is driven over extremely rough roads or off-road conditions, the engine speed may become erratic. This can cause the PCM to interpret it as an engine fault, such as a misfire.
Some vehicles may have a road sensor, an accelerometer, or they may use ABS wheel sensors and the Electronic Brake Control Module (EBCM) to determine rough road conditions.
Regardless of the specific system used in your vehicle, if you encounter this trouble code, it means that the PCM has detected a rough road condition that requires attention. Typically, this code is only set after consistent readings are obtained during multiple drives. This code specifically refers to the electrical circuit of Rough Road Sensor A.
Symptoms
Most trouble codes trigger the check engine light (or MIL malfunction indicator light). However, in the case of this P0318 DTC, the light does not illuminate. However, you may notice other warning lamps illuminated (traction control, ABS, etc.) or experience engine misfires or rough running.
Causes
Possible causes for this code to be set include:
Diagnostic and Repair Procedures
A good initial step is to check for technical service bulletins (TSBs) that may be applicable to your specific year/make/model. If the issue is a known problem, there may be a bulletin available to assist with diagnosis and repair tailored to your exact problem. This can save you time and money.
You should obtain a vehicle-specific repair guide to determine the exact type of rough road system used in your vehicle.
If you have other misfire, ABS, or related codes, it is generally recommended to address them first before attempting to fix a P0318. However, it is important to record all freeze frame data as it may be useful in the overall diagnosis.
If your vehicle is equipped with an accelerometer sensor, check the condition of the sensor, wiring, and connectors for any issues. Repair as necessary. Then, use a digital volt ohm meter (DVOM) to check the continuity, resistance, and other electrical aspects according to the manufacturer’s specifications.
If possible, utilize an advanced scan tool to drive the vehicle over rough roads and monitor the sensor readings from the appropriate sensors on the vehicle. This can help in duplicating the issue and narrowing down the location of the problem.
