What Causes Spark Plugs to Wear Out?

Without operational spark plugs, your engine won’t run. If even just one plug were to fail, the change in functionality would be very noticeable. Your engine would run rough, it would idle poorly, it might spit and sputter during acceleration, and it might even stall out on you. Spark plugs do wear out over time, although the actual lifespan varies depending on the type of plug in question, the condition of your engine, and your driving habits.

Wear factors for spark plugs

There are several factors that play a role in spark plug health, but the most common reason for them to wear out is that they’re just old. To understand this, you need to know a bit more about how spark plugs work.

When your alternator generates electricity, it is sent through the ignition system, down the spark plug wires, and to each individual spark plug. The plugs then create electrical arcs at the electrodes (the small metal cylinders protruding from the bottoms of the plugs). Each time a plug fires, a minute amount of metal is removed from the electrode. This shortens the electrode, and requires more and more electricity to create the arc necessary to fire the cylinder. Eventually, the electrode will be so worn that it won’t arc at all.

This is what happens in a normal, properly maintained engine. There are other factors that can reduce plug life (all spark plugs eventually wear out; it’s just a question of when).

  • Overheating Damage: Overheating spark plugs can cause the electrode to wear faster. Pre-ignition from an improperly timed engine can cause this, as can an incorrect air to fuel ratio.

  • Oil Contamination: If oil seeps onto the spark plug, it will foul the tip. This creates damage and additional wear (oil seeping into the combustion chamber is something that happens over time as seals begin to fail).

  • Carbon: Carbon buildup on the tip can also cause premature failure. This can happen due to dirty injectors, a clogged air filter and many other reasons.

As you can see, there are a number of different factors that affect when your spark plugs will fail, and just how much use you’ll get out of them.


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Pardeep

21 years of experience
1068 reviews
Pardeep
21 years of experience
Jeep Cherokee V6-3.2L - Spark Plugs - Cupertino, California
Great service. Looking forward to build a good relationship different from the usual mechanics that is always trying to charge you more. Pradeep made me the impression that he is different. Cool.
Toyota Prius - Spark Plugs - Fremont, California
Mr. Singh was on time, gave good advice and did the services very well. By the way, this is the third time I have my car serviced by him.

Keven

7 years of experience
118 reviews
Keven
7 years of experience
Kia Soul L4-2.0L - Spark Plugs - Puyallup, Washington
Kevin, is wonderful. He is on time and very efficient. He explains things very well and answered all my questions. Very friendly too. I would highly recommend Keven and plan on using him again if mechanic service is needed.
Toyota Sienna - Spark Plugs - Spanaway, Washington
He was very efficient, very knowledgeable and very sweet. Thank you for your time and your patience with my vehicle.

Claud

8 years of experience
475 reviews
Claud
8 years of experience
Dodge Durango V8-4.7L - Spark Plugs - Detroit, Michigan
On time, very knowledgeable, and professional. Excellent job, thank you. Will call for service again.
Ford Flex - Spark Plugs - Rochester, Michigan
Claud did a great work for a big job on my car. Brought it back from the dead. Will definitely be booking him in the future.

Rodney

36 years of experience
541 reviews
Rodney
36 years of experience
Volkswagen CC L4-2.0L Turbo - Spark Plugs - Sacramento, California
Awesome mechanic worked really fast and help me understand a lot more about my car honestly I didn’t know much and he was really helpful and definitely will be booking with him again
Jeep Cherokee - Spark Plugs - Elk Grove, California
I’m so pleased with Rodney, he’s very thorough. This is my third time using Rodney (Your Mechanic). I have no complaints. I appreciate him repairing my vehicle.

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