How to Identify a Fouled Spark Plug

by Contributor

When you own a car, you can save yourself a lot of money by learning how to do simple repairs yourself. One such repair is changing the spark plugs. If you don't change them when they are fouled, you will get less gas mileage and poorer engine performance. Here are some tips to identify fouled spark plugs so you can change them.

Remove the spark plug from your engine. You will need the owner's manual for your specific car as well as a spark plug puller. This will allow you to remove the plug easily. Also, make sure the engine is off and the keys are not in the ignition.

Look at the spark plug once you have removed it. The definition of a fouled spark plug is if oil, dirt, fuel or other debris has corroded the tip. The tip should be clean and clear so that the spark travels cleanly to the tip.

Wipe away the dirt, oil gas and other debris with a rag. If you can remove this easily, then you might be able to save the spark plug. However if the corrosion stays on the spark plug, then it is truly fouled and needs to be replaced. Bring the spark plug to your nearest auto parts store so you can ensure that you get the proper make and model for your vehicle.


  • check If you really aren't sure what you are doing, have a mechanic look at your car. You don't want to cause more damage or overlook a more serious engine problem.

Items you will need

About the Author

This article was written by the It Still Runs team, copy edited and fact checked through a multi-point auditing system, in efforts to ensure our readers only receive the best information. To submit your questions or ideas, or to simply learn more about It Still Runs, contact us.

More Articles