How Can I Tell if My Spark Plugs Are Bad?

Your car, SUV, or truck will start to act up if the spark plugs are bad. The spark plugs generate sparks in the cylinders to ignite the air and fuel in the cylinders. This starts your car by generating engine combustion. The spark plugs continue to ignite the air and fuel while your engine is running. If your spark plugs are going bad, you will have one or more of the following problems.

Difficult Starts

It can be difficult to get a vehicle started if the spark plugs are bad. If one plug fails to generate a spark, the engine will have a hard time generating combustion. If all of the plugs are bad, there will be nothing to ignite the air and fuel and the engine will not start at all. If you are having a hard time getting your vehicle started, head to our shop so we can inspect the plugs and replace them if necessary.


Faulty spark plugs will also make the cylinders misfire. You may have one or more plug that does not generate a spark, and, as such, that cylinder will not fire. This will make your engine cut out and your car jerk when it’s time for that cylinder to fire. Consequently, your car will act as if it has the hiccups. In severe cases, i.e., several cylinders aren’t firing, the engine will stall and you’ll have to restart it.

Rough Idling

One of the most common instances when the engine stalls is while you are sitting at an idle. This is also the best time to notice that the engine is misfiring. You will be able to feel easily that your car is jerking. You can also listen to the engine carefully and hear when a spark plug does not fire in a cylinder.


The engine cuts out when a spark plug does not fire in a cylinder, and this can make your engine lag. The engine will also sputter and you may have problems accelerating your vehicle. Unfortunately, the opposite can also occur with worn spark plugs. Your engine may surge if the plugs fire multiple times.

Poor Economy

Finally, the engine performance issues discussed above will have a direct effect on your fuel economy. Unfortunately, your engine will become a fuel hog, and you will get rotten fuel mileage.

Do not hesitate to bring your vehicle to our shop if you think the plugs need to be replaced. We will inspect them and recommend the proper course of action.

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