How Long Can You Drive With Bad Spark Plugs? (Explained)

Spark plugs may look small, but their responsibility is quite heavy. Therefore, it’s important to maintain their performance and keep an eye on how they are performing.

It would not be a wise decision to continue driving while something is not right in the performance. When you have noticed that spark plugs are gone bad, it’s best to take the vehicle to the mechanic for immediate repair.

However, sometimes you get the flexibility to delay the repair. For example, when the spark plugs of the car have gone bad for some reason, you can still choose to drive about 80,000 miles.

Ideally, you must wait for the problem to get worse because if you keep on driving with bad plugs, it can cause some costly damage to the engine that you will certainly not like.

Let’s explore more about spark plugs!

What does spark plug do?

Spark plugs in the car offer power to the engine by igniting the spark. The spark is to ignite the air/fuel combination in order to start the vehicle for the combustion. Therefore, it’s important to keep these plugs cleaned from any dirt or grease build-up. Also there should not be any damage  or defect in the electrodes.

Why do spark plugs go bad?

Many people are annoyed with the bad spark plug in the car. As you know the spark plug does the job as its name suggests, igniting the spark in the engine for the combustion process

So when the tip of the spark plug overheats, it becomes faulty for good. In fact, overheating of any component in the car can cause failure or malfunctioning.

What can permanently damage the spark plug?

Here are the few things that cause damage to spark plugs.

Accumulation of carbon

Another reason spark plug failure is the buildup of carbon is killer for spark plugs. The blackish soot of the carbon works as the insulator and certainly that keeps off the ideal current flow of the ignition process. 

Not only this, the carbon can also damage the spark plug and decrease its durability to a greater extent. If you don’t keep the plugs well-cleaned, the carbon accumulation is obvious.

The gap in spark plug

The gap in the spark plug can cause damage as well. The right gap matters and if you exceed it, it can impact its performance. More gap between the spark plug’s center and side electrodes means more stress and it can damage the tip of the plug permanently


The overheating of spark plugs makes them inefficient for performance and they become permanently defective. 

Overheating can be due to things like pre-ignition and a malfunctioning cooling system. Pre-ignition causes overheating in the combustion chamber causing failure in spark plugs.

Oil in Combustion Chamber

The oil will prevent the plugs for smooth and quick spark. When oil leaks into the combustion chamber, it can make the spark plug tip oily and the dairy tip will no longer ignite the spark. Make sure the car dies soon to burn oil, as it’s the sign of oil in the combustion chamber.

Read Also: Can Low Oil Cause Check Engine Light to Come On

Indications for worn-out spark plug

  • Reduced Gas Mileage
  • Poor Acceleration
  • Hard Starts
  • Engine Misfires
  • Rough Idling

If you find any of these signs, it’s best to replace the older spark plugs with new ones by taking your car to the mechanic.

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