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May 14, 2023

How many spark plugs does my vehicle need?

One of the most common questions mechanics get is, “how many spark plugs does my vehicle need?” While you might expect a long and involved answer, the answer is actually quite simple. Generally speaking, your engine requires one spark plug for each cylinder the engine has.

That means a four-cylinder engine has four spark plugs; a V6 has six, a V8 has eight, and so on. Of course, the answer to “how many spark plugs does my vehicle need” comes with a follow-up question regarding if an engine can operate properly if one or more spark plug isn’t functioning. Unlike the first answer, this question needs a little more information to satisfy.

What Does a Spark Plug Do?

Spark plugs are the device that ignites gasoline and air in the engine. The spark causes the air/gas mix to combust, which drives the pistons and thus allows your engine to function. Without sparkplugs, there is no ignition, which makes an internal combustion engine a very expensive paperweight. 

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Do All Cars Require Spark Plugs?

You might think any vehicle that uses some form of gas needs spark plugs to operate. Obviously, electric vehicles don’t need to produce any kind of ignition to operate. Diesel engines also do not require spark plugs to operate. Instead of using a spark to ignite the gas mixture, diesel engines use compression and pressure to great the heat that ignites the fuel mixture. Diesel fuel essentially self-ignites when it’s sprayed into the cylinder in a mist form.

Can a Car Run Without Functioning Spark Plugs?

If you had a single-cylinder engine with a broken or missing sparkplug, the engine wouldn’t work. Since most automotive engines have multiple cylinders, you can technically run with only one of the spark plugs in operation. Unfortunately, missing one or more functional spark plugs can result in instabilities in your engine’s crank, which could cause serious damage to your vehicle.

How Do I Know If a Spark Plug Needs to Be Replaced?

When a spark plug starts to fail, you’ll notice a number of problems with the engine, including a rough idle, problems starting the engine, higher-than-normal RPMs (surging), increased fuel consumption, and poor acceleration. Most mechanics recommend replacing your spark plugs between every 80,000 and 100,000 miles. Most spark plugs are designed for long-term durability, so they may only have to be changed a couple of times during the life of the car. Of course, high-performance plugs tend to wear down a little faster. Spark plugs can also be damaged during the use of your car, which requires intervention a little earlier. For example, if oil leaks into the combustion chamber, it can cause the tip of the spark plug to get oily and dirty, which can interfere with the plugs sparking ability.

How Many Sparks Plugs Does My Vehicle Need?

In summary, if you have a diesel engine or an electric vehicle, you don’t need to worry about spark plugs. Your car should have as many spark plugs as it has cylinders. Technically, an engine can run so long as at least one spark plug functions, but running with any spark plugs out of order can damage your engine. To keep your engine running its best, it’s always wise to change or repair your spark plugs whenever necessary. For more information, read our article called What You Should Know About Spark Plugs, Their Adjustment, and Their Replacement.