Should I Replace Ignition Coils With Spark Plugs?

Published: 09/14/22 •  4 min read

Many vehicles have internal combustion engines. These engines require three components to run smoothly: fuel, air, and electricity. The engine will not function if one or more of these components are missing. 

The ignition coils partly supply the electrical component. The vehicle’s performance may suffer if the ignition coils fail to function properly.

Before we answer the question “Should I Replace Indicators With Spark Plugs?”, it is crucial to understand what an ignition coil and spark plug is.

Ignition coil vs. Spark Plug

An ignition coil is an electronic device that “converts” digital pulses from your car’s computer into an analog signal that is then sent to the spark plug wire. 

Spark plugs are responsible for creating a small, powerful electric discharge to ignite the gasoline or petrol mixture before it enters your car’s combustion chamber.

The secondary winding creates an arc between electrodes when electrical energy is released. This ignites the combustion chamber and then sends power to the engine pistons.

Because a car’s battery produces a low voltage current, which is not strong enough for the engine to start on its own, ignition coils are required. The ignition coils transform the low voltage current from a battery to a much higher voltage.

Simply put, ignition coils allow the spark to be generated and the vehicle to start and run.

Different Cars Have Different Kinds of Ignition Coils

Modern vehicles use the most common type, coil-on-plug, with one ignition coil connected to each spark plug. Some vehicles have a central coil pack, while others have individual coils that lead to the spark plugs. A smaller percentage of vehicles use one coil per two spark plugs, while two ignition cassettes power half the spark plugs.

You may also like: How Many Ignition Coils Does a Car Have?

Are the Ignition Coils the Same as the Spark Plugs?

Spark plugs and ignition coils do not have the same characteristics. Two wires go to the ignition coil. One is for the battery voltage; the other is to control the timing of the spark. 

A “coiled” coil has a spiral of wire wrapped around a magnet core, strengthening the magnetic field. This coil generates an extra voltage to create an electric discharge that can ignite the gas. Because they are smaller than the coils in cars, coil-on-plug ignition systems have replaced them. 

Modern vehicles use high-octane gasoline instead of gasoline so that these smaller coils wouldn’t be strong enough.

An ignition coil is attached to the spark plug, which triggers an electromagnetic response when necessary. The spark plug sends an electrical current to the spark gap and causes ionization.

Should I Replace Ignition Coils with Spark Plugs?

It depends. 

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Spark plugs and ignition coils are closely related. The one that fails will cause the other to stop working correctly. 

Spark plugs are the most commonly replaced component in conjunction with ignition coils. Worn-out spark plugs can put unnecessary strain on the coils. There is also a possibility of overlap in labor costs. It is a good idea to replace both the spark plugs and ignition coils if they fail.

However, your spark plugs don’t need to be replaced unless you have signs of failure. 

Replacing the ignition coil or spark plug wires is a good idea if they are damaged or worn out. To prevent moisture damage to the ignition coils (such as oil leaks), it is crucial to address the source of the moisture immediately.

WHEELSCRIBE recommends contacting a mechanic immediately if you have ignition coil problems. Let your mechanic inspect your vehicle and determine if your spark plugs need to be replaced or not.

Cost of Replacing Ignition Coils

Simple coil-on-plugs can cost as little as $100, while a cassette-style system could run up to $1000. The cost of an ignition coil depends on the coil style and the difficulty of access.

What If You Don’t Replace an Ignition Coil?

Vehicles with one or more defective ignition coils can have poor power, run poorly, or not at all. A misfiring engine can also cause damage to the oxygen sensors and catalytic converters. This is due to unburned fuel getting into the exhaust system.

If your ignition coils are not working correctly, you should stop driving your vehicle. You could endanger your engine by driving a vehicle that has failed ignition coils.