Auto Systems and Repair: Spark Plug
Symptoms of Wear or Failure
- Check Engine Light may come on or blink
- Engine may run roughly
- Abnormal engine noise due to loose or missing spark plug
Related Repair Advice
- Failing spark plugs can cause the engine to run rough and misfire, which can trigger the Check Engine Light. Continuing to drive under these conditions can damage the catalytic converter.
- Engines may have one or two spark plugs per cylinder and each spark plug can have from one to four electrodes
- Replacing spark plugs can be labor intensive on some late model vehicles
- To prevent ignition misfires and Check Engine Light problems, we recommend using only high-quality spark plugs, and preferably spark plugs from the OEM
- Spark plugs have different ratings and it's important that the correct type are used
- Spark plug terminals wear down over time and can lead to engine misfires. At a minimum, they need to be replaced at the mileage specified by the vehicle manufacturer.
- Manufacturer's instructions should be followed when removing spark plugs. Cylinder heads made from aluminum can be damaged if the correct procedures are not followed.