Everything You Need to Know About Car Ignition Coil Replacement

As your car grows old, it demands constant repairs. So now if you are facing issues with the ignition coil, you need to get it replaced. There might be several queries popping up in your mind like how much time will it take to replace? You would be looking for an estimate of the repair costs. Let’s learn everything you need to know when it comes to car ignition coil replacement.

Function Of The Ignition Coil

What is the purpose of the coil? The ignition coil acts like a high voltage low current transformer that gives electricity to the spark plugs that can ignite the fuel-air mixture and start the engine. It is one of the essential components of the ignition system as your car won’t start without it. Also, your engine might suffer from difficult starting conditions or sudden stalling.

car ignition coil

When your car fails to start, it probably appears to be a problem in the engine. However, sometimes the issue could appear in the ignition coil, and one must always check it before getting into the engine. 

Car Ignition Coil – Testing

How to check if your car ignition coil is failing? Well, either you can reach a mechanic, or you can determine the same by performing a simple test.

car ignition coil
  • Get a digital ten megaohm impedance the ohmmeter and connect it to the negative and positive terminals of the ignition coils. Read off the numbers that should be between .04 and 2 ohms. If the ohmmeter reads zero resistance, that means the coil is short, and if it reads high resistance, that means the coil is open. 
  • Another way to figure out the car ignition coil replacement is by using a spark tester. Please turn off the engine first and then disconnect the coil from the spark plug, connecting its top to the one end of the spark tester and the other end to the coil output. Now, start the engine. If the light flashes on the spark tester, it means that the ignition coil is working correctly. In case no light appears, it denotes that you have faulty ignition coils that need to be fixed immediately. 

Signs of Bad Ignition Coil

As you now know that without ignition coils, your car won’t start. Therefore, you must be aware of the signals of a bad ignition coil. The most common problem is the misfires. It needs to be addressed as it could damage other parts of the engine.

In modern engines, each cylinder has multiple spark plugs. The ignition coil is connected directly or through special wires to each of these spark plugs. Thus in case ignition coils are not working, it would mess up the entire system. 

Here are some of the most common symptoms of a bad ignition coil.

Engine Backfires: 

Engine backfires are easily recognizable before the ignition coil deteriorates. Before that, are you aware of what happens during engine backfiring? Well, it is the unused fuel leftover in the internal combustion cylinder that starts flowing in the form of black smoke through the exhaust pipe. 

car ignition coil

The smell of gasoline also indicates a problem with the ignition coil.

Engine Stalling:

While driving a regular route at nominal driving speed, if you notice your engine stalls after a couple of miles, it indicates terrible car ignition coils. The stalling happens because the ignition coils do not supply regular current to the spark plugs. For the smooth working and running, the car requires constant current and its absence would completely stop the vehicle causing further damages. 

Engine Light: 

There is a check engine light that turns ON if there is a problem in the car engine. This notification is mostly related to the ignition coils demanding immediate action. When there are issues in the ignition coil, your engine light starts blinking as they are directly connected. Take care of it and get your car ignition oil replacement.

car ignition coil

Loud Engine Noise: 

Have you been noticing excessive noise from your car engine? These are all the symptoms of lousy ignition coils as when they are not able to generate enough voltage for the spark plugs; your engine works harder to continue to run. Since it is overworked, it starts making loud sounds and vibrations.

Poor Fuel Economy: 

Faulty ignition coils won’t pass enough electricity to the spark plugs that would make the engine use more fuel. It would eventually drop your gas mileage. 

car ignition coil

Car Doesn’t Start: 

Your car engine might not start at all if your ignition coils aren’t working with full capacity. It makes a clicking sound.

Car Ignition Coils Replacement

Once you get to know that your ignition coils are not working correctly, you need to find the correct tools to replace them. If you cannot do it by yourself, you can visit your nearby mechanic. 

car ignition coil

Replacing on your own: Disconnect the car battery and then using the wrench, unscrew the bolts and remove the negative terminal. You can find the ignition coils on the top of the engine. Remove it using the wrench and then disconnect the electrical connectors. 

Now, install the new ignition coils. Make sure to bolt tight and reconnect the electrical connections. Put everything back together in its original way. 

Lastly, reconnect the battery’s negative terminal. Start your car and take a test drive making sure that there is no misfire or stalling. This smooth-running ensures that you are successful in installing the ignition coils.

Cost of Replacing The Ignition Coil

Getting your car continuously repaired adds up to higher costs. It is better either to replace the ignition coils on your own or to get it done from a mechanic for which you will need to pay labor costs. 

The cost of fixing the ignition coil runs between $265 and $375, including the cost of labor and the auto parts. The work usually costs from $99 to $125. Therefore if you replace it on your own, you can save a lot. The auto parts cost you between $165 to $250, and the rest it all depends on which part of the ignition coil requires replacement.


Car stalling or misfiring are the signs of a faulty ignition coil. If you notice such issues, you need to resolve these problems with the car ignition coil immediately as it can further damage your car engine to the extent that your car will stop working altogether. The Auto Parts Shop takes pride in selling auto parts at the best prices. Contact us today and get rid of expensive repair bills.

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