Spark Plugs: What Are They & Why Are They Important?

image with text spark plugs: what are they & why are they important

The spark plugs on your engine are more than just confusing bits of metal. They are complicated pieces of technology that send electrical energy to the combustion chamber in your engine. This little spark sets off the “explosion” that creates controlled chaos in the chamber and starts your engine. Not a small role, by any means. 

How Does it All Work?

The spark plugs sit on top of the cylinder head of your engine. As the pistons in your car travel up and down, they draw in a mixture of air and fuel, compressing it. At the very last second, as the pistons reach top dead center (TDC), the spark plug lets off a little jolt of electricity and lights the mixture. The piston heads back down, thereby creating power for your car, and back up again to clear the exhaust. The process continues to cycle as your car runs.

Something that may surprise you: while 4-cylinder engines have 4 plugs, and 6-cylinder engines have 6 plugs, diesel engines have 0 spark plugs. This is because diesel engines run at higher compression ratios and the combustion starts without needing a spark.

When Should You Change Your Plugs?

As you can see, spark plugs play an important role in your car’s operation. You need to keep a careful eye out to see if your spark plugs are going bad. Some symptoms include:

  • Your car refuses to start
  • Your check engine light comes on
  • Your car doesn’t want to accelerate quickly
  • You have to fill up your gas tank more often
  • The engine starts pinging, rattling, or knocking

You should be able to get about 80,000 miles out of your spark plugs before they need to be replaced. It’s important not to keep driving on worn-out spark plugs but replace them or take them to a professional to be replaced.

Contact Performance Auto today to speak with our honest and qualified team. Let us take care of your car repair today!


  1. Spark plugs are really important. Mostly during winters the spark plugs stop working which creates problems big time. I have experienced it myself therefore I know the importance of spark plugs.

  2. I never knew that diesel engine didn’t require a spark plug! That’s surprising cause I though all engines had a spark plug to ignite the process!

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