P0318Generic code

P0318 Code: Rough Road Sensor A Signal Circuit

The P0318 code means there is a fault in the signal from rough road sensor A, which the computer uses so it does not confuse bumps with misfires. The engine runs normally and you can keep driving. The usual fix is a wiring repair or a new sensor.

Severity
Low
Can I keep driving?
Yes, no immediate risk
Estimated cost
$30 to $250
Difficulty
Medium
System
Ignition and Misfires
Applies to
All OBD2 vehicles

Updated Reviewed by Renzo Chacca

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What the P0318 code means

Some vehicles carry an accelerometer (the rough road sensor) to detect vibrations coming from the road. When the road is very rough, the computer temporarily suspends misfire detection. The P0318 code means the signal from sensor A is missing or wrong.

Without this signal, false misfire codes can show up on dirt roads. The engine runs normally.

P0318 code symptoms

  • Check engine light on.
  • Possible false P0300 codes on rough roads.

Likely causes of the P0318 code

  1. Damaged sensor.
  2. Connector or wiring.
  3. Sensor power supply.

How to diagnose the P0318 code step by step

  1. Inspect the sensor connector.
  2. Check the power, ground and signal.
  3. Verify that the vehicle has the sensor. Some use the ABS instead.

How to fix the P0318 code

  • Repair the wiring or replace the sensor.

After the repair, clear the P0318 code and check that it stays gone after a drive over uneven pavement.

Technical reference data

  • On most vehicles the sensor has 3 wires and a 5 V reference.
  • These values are for orientation only. Check the manufacturer data for your engine.

Brand-specific notes

P0318 on Ford

Some Ford vehicles from the late 1990s and early 2000s use this sensor.

P0318 on GM

Some GM vehicles from the late 1990s and early 2000s use this sensor.

Frequently asked questions about P0318

Does it affect the engine?
No. The engine runs normally, and the only side effect is possible false misfire codes on rough roads.
Can I drive with a P0318 code?
Yes. It is a low severity code and does not limit the engine.
Where is the sensor?
It is usually on the chassis or next to the computer. Check the service manual for your vehicle.
How much does it cost to fix P0318?
Between $30 and $250, depending on whether it is wiring or a new sensor.
What does the P0318 code mean?
It is a generic OBD2 code that means the signal from rough road sensor A is missing or incorrect.
What is the most common cause of P0318?
A damaged sensor, or a connector or wire problem in its circuit. Check the connector and the 5 V reference first.

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Questions about the P0318 code

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