Tips for Buying a New, Inexpensive Ignition Coil

This buying guide will help you understand what exactly an ignition coil is, and what you need to look for when you're buying a replacement part.

Similar to a Transformer: How Ignition Coils are Constructed

In order to understand what an ignition coil does in your car, we'll first explain what kind of a component it is. An ignition coil is fairly similar in its construction to a transformer or an autotransformer, which the name“ignition coil”already hints at a little bit. But it's not that easy to explain how an ignition coil works. Once you turn on the ignition in your car, current flows through the ignition coil. This creates a magnetic field which, to put it simply, creates a pulse of high voltage. The high voltage is transmitted to a spark plug, which then causes the mixture of gas and air in the cylinder to ignite. Basically, the ignition coil is responsible for the ignition function in your car and for helping your car burn fuel.

This explanation is highly simplified, of course, and the physical processes are much more complex. Spark plugs are only found in gasoline engines, which means that ignition coils are also only used in gasoline engines. Diesel engines get by without them.

The ignition coil needs two helper components to be able to function. The first is a circuit breaker, and the second is the alternator. Only when these three parts work together can the ignition coil create enough voltage to be able to help light the fuel. Here are a few numbers: the ignition coil along with the circuit breaker and alternator can convert typically available 12 volt power into a high voltage of 15,000 to even 30,000 volts.

 

Electrical Issues: Ignition Coils and Wear

Not every car has just one ignition coil. Cars have one spark plug per cylinder, so there may be a separate ignition coil for each cylinder as well. A four cylinder car can have four coils, although cars often have double ignition coils which work with two spark plugs each and two cylinders. Ignition coils are part of your car's electrical system, which is the cause of lots of issues on modern vehicles. Ignition coils unfortunately aren't exempted from electrical issues. Quite the opposite, in fact – the ignition system continuously ranks as one of the most-repaired systems in your car.

Nevertheless, ignition coils can last for a relatively long life, and on average last 10-15,000 miles or more. Gas engines which have been converted to run on natural gas, or commercial vehicles which do, experience quicker wear to the ignition coils. There are not many studies yet on how natural gas affects ignition coil, but it seems that it needs to create more power. More energy use and greater stress on the part causes quicker wear.

 

One Thing's For Sure: You Won't Go Anywhere Without an Ignition Coil

Generally, all your ignition coils won't go out at the same time; just one normally goes out at a time. If you have a four-cylinder car, this means one cylinder will be affected (or two if you have a double ignition coil). Your car will actually still run, but you will see major consequences from a failed ignition coil.

If the ignition coil isn't working correctly, the spark plug won't be supplied with high voltage and won't create any sparks. The consequence is that the gas in the cylinder won't be lit and won't burn. This has even more consequences. First of all, the unburned gas will end up in your exhaust system. Here, unburned fuel will hit the hot catalytic converter and will suddenly ignite. This causes excess wear to your catalytic converter. This would mean you'd need to eventually replace it, which can cost several hundred dollars extra.

A second direct consequence of a defective ignition coil will be obvious when you look at your speedometer. If one or possibly two cylinders aren't functioning, your engine won't be able to deliver the power you're used to. A defective ignition coil would lead to poor pick-up or low top speed.

And on top of all this, your ignition system works in direct concert with your catalytic converter, which controls the emissions your car produces. If the ignition system isn't working right, the same thing is true of the catalytic converter. Your car will have less ability or possibly no ability to stop emissions from escaping the car, which causes toxins to be released into the air at rates up to ten times worse than normal.

 

Signs of a Defective Ignition Coil

Just because your car doesn't stop driving altogether when your ignition coil goes out doesn't mean you should just keep driving on it. All that gas you aren't burning is just a waste of money and threatens to damage your sensitive catalytic converter. Even as a lay person, you can recognize an ignition coil that's having issues. Besides noticing a decrease in power, you'll see a few other symptoms.

For example, your engine will run much rougher than normal. You'll notice your throttle is less responsive, especially when the engine is cold or running at low RPMs. It could take the car one or two seconds longer than normal to start up. Over time, you could even start to notice engine misfires if you don't react to the signs or don't notice you have a problem with your coil. Normally, you should also see a warning light on the dash, although it might not tell you specifically that your ignition coil is the issue.

Once your defective ignition coil starts to damage other components in the vehicle, you'll notice even more symptoms. The ones named above, however, are the most common signs of a defective ignition coil.

 

How Much Does a New Ignition Coil Cost?

If your car has around 50,000 miles on it, don't be surprised if you need a new ignition coil soon. Some coils can last up to 25,000 miles longer or fewer. The price of a new coil is usually between 100 and 150 dollars, although it can be more depending on the vehicle. You can find much better deals online if you're willing to look. You could even consider a used ignition coil.

There are some things to think about when you're buying vital car parts. First of all, your new ignition coil has to fit your car's make, model, and engine. It's not difficult at all to find the right ignition coil for your car, however. Just use the search criteria at the top of the page on Superspares our website to narrow down for your make, model, and year.

Any hobby mechanic who's spent a little time under the hood should be able to install a new ignition coil in their car. The only issue you might encounter is that some manufacturers and some car models require you to use a specialized tool to remove the coil. Normally, the tools you already have in your garage will do the job.

The actual process of changing the ignition coil isn't very complicated. One tip: besides any ignition coil pullers and a good socket wrench, a little rust-remover might be helpful. You should have the job done in just a few minutes. Here's a short overview of what you need to think about when you're doing the repair, and a list of the basic steps you'll follow:

 

Instructions for Changing Your Own Ignition Coil

First, disconnect your car's battery. If you haven't done this before, find a way to mark the connectors so you'll be able to reconnect it again correctly later. Now, remove the ignition coil itself by unscrewing the screws which connect it to the rest of the electrical system. You might need a little rust-remover, which you'll need to let sit a few minutes to do the job. Using force isn't a good idea – you could damage the car or injure yourself.

Once you've disconnected all the screws, you can remove the old ignition coil. Follow the reverse procedure and make sure all the screws are secure. Then reconnect the battery and double-check all the connections and plugs. This is really all you have to do to replace an ignition coil.

If your spark plugs are also a few years old, it's a good idea to change them out when you change the coil. Over the years, spark plugs change their level of resistance, which can restrict the function of the ignition coil as well in some cases. Old spark plugs can cause the ignition coil to wear out more quickly, so change them at the same time. Often people will change out all the coils at once instead of doing so individually. If you have a four-cylinder car, this could double or even quadruple the cost, but it's still not a bad idea. If you have a newer car, you may actually have everything in one complete module which will be changed out altogether.

Unfortunately, not every car will be as easy to exchange a defective ignition coil on as we've stated in this guide. Some manufacturers or car types can cause extra problems, possibly by requiring extra tools without which you simply can't do the job. Before you start, look at how easy or difficult it is to reach the ignition coil in your car. It's also a good idea to take a look at your owner's manual before you begin.