In order for your spark plugs to spark, they require a very high voltage charge to ignite the air/fuel mixture. This is achieved via the ignition coil in petrol cars. These coils are very important and if one starts to act up then it can lead to misfires and a whole bunch of problems down the track.

What is an ignition coil?

An ignition coil sits atop your spark plug assembly and receives a charge from the ECU which it then sends through its many coils creating a magnetic field which is then sent to the spark plug. Because of the magnetic field, the voltage turns from 12 volts to over 40,000 volts!

This creates a strong spark that effectively combusts all the fuel in the chamber and ensures you get the maximum bang for your buck. 

Why do you need an ignition coil? 

An ignition coil is what’s used to power your spark plugs. If it starts playing up, your spark would be weak and your car wouldn’t run properly. It also means that the car wouldn’t be as efficient and you’ll burn a lot of gas in the process. It’s important to the engine's longevity that these are in good working condition.

How to tell if you need a new ignition coil

If your car develops a misfire, starts running really rich (you can smell the petrol coming out of the exhaust), your fuel consumption goes up, or your car runs really rough. These are usually indicators that your ignition coil is on its way out and needs replacing.

How is an ignition coil replaced?

Firstly the mechanic will remove the engine coverings and locate the coils. Then they will be unclipped from the spark plug and sometimes swapped with another to check if it is just that coil playing up. Once the faulty one is found, it will be removed from its mounting and disconnected from the wiring. The new coil will be connected and the engine will be run. The mechanic will lastly, scan the engine computer and make sure that the fault is gone.

How much does an ignition coil replacement cost?

They are a pretty high tech part, but not super difficult to replace. Prices for an ignition coil replacement start at around $200 and can go over $800 for the high end parts.

How often do I need an ignition coil replaced?

They last a good while in the right settings. Typically these won’t fail you under 100,000km unless you have a turbocharged car in which case they can fail around every 65,000km.

Is a broken ignition coil unsafe?

It won’t affect your safety but it will damage your car. Your catalytic converters will slowly fill up with carbon from the unburnt fuel. Your valves will become clogged and your fuel economy will slowly get worse and worse. 

Best practice is to replace them as needed.

You can find a mechanic near me with My Auto Shop