An ignition coil is an important part of your car’s ignition system. It is responsible for transforming the 12 volts of electricity from the battery into the thousands of volts needed to spark the fuel in the engine. If your ignition coil is bad, it can cause a number of problems with your car, including a misfire or no start. In this blog post, we will discuss what an ignition coil is, the symptoms of a bad ignition coil, how much it costs to replace it, and much more. Read on to learn more about ignition coils and what it takes to replace one!
What is an ignition coil and what does it do?
An ignition coil is a type of transformer used in spark-ignition internal combustion engines to produce the electric spark that ignites the air-fuel mixture in the combustion chamber. The purpose of an ignition coil is to take a low voltage from the car’s battery and transform it into a much higher voltage, which can then be sent to the spark plugs and ignite the air-fuel mixture.
Working of the ignition coil
Ignition coils are typically composed of a primary coil and a secondary coil. The primary coil, which is wrapped around an iron core, receives the low voltage from the battery and amplifies it by magnetically inducing a much higher voltage in the secondary winding. This high voltage is then sent to the spark plugs via the spark plug wires and then ignites the air-fuel mixture in the combustion chamber.
Importance of the ignition coils
The ignition coil is an essential component of a spark-ignition engine and its proper functioning is necessary for reliable engine operation. Without the high voltage generated by the ignition coil, it would not be possible to ignite the air-fuel mixture in the combustion chamber and allow the engine to run. As a result, it would be impossible to start your car’s engine. Additionally, faulty ignition coils can cause issues such as rough idling, poor acceleration, misfires, and stalling. Therefore, it is important to make sure that your car’s ignition coils are in good working condition.
For this reason, it’s important to ensure that the ignition coil is in good condition and regularly maintained.
Ignition Coil Location
Typically, it is located either near the engine or on top of the spark plugs. The coil can be found under spark plug wires, or as a single unit with multiple high-tension leads.
Symptoms of a Bad Ignition Coil
If your vehicle is having issues driving smoothly, it could be a sign that the ignition coil needs to be replaced. Intermittent behavior and difficulties controlling the car are two telltale signs of an aged or faulty ignition coil. Failing or worn-out ignition coils can cause a variety of issues, depending on their severity. If you’re suspicious that your vehicle’s coil isn’t performing optimally, look out for these telltale signs:
Misfiring Engine
When an ignition coil on a vehicle fails, it can have serious implications for the vehicle’s performance. The most obvious symptom of a misfiring engine is a coughing or sputtering noise when starting up, which is caused by incomplete combustion in the cylinders. This type of problem will also present itself during high-speed driving with jerking and spitting motions. Additionally, when the vehicle is idling at a stoplight or other location, it will shake and vibrate due to the misfiring. All of these symptoms indicate that the ignition coil needs to be replaced.
Vehicle Stalling
When an ignition coil fails, the vehicle can suddenly stall or even shut off while driving. This is caused by a lack of spark supplied to the spark plugs due to the faulty coil. The engine will fail to keep running when this occurs, which can be alarming and dangerous if it happens in traffic or on the highway. If you encounter this problem, it’s best to have your vehicle inspected by a professional and get the coil replaced if necessary.
Backfiring

When combustion isn’t firing properly, it can cause unsatisfactory exhaust emissions, which can result in loud pops or bangs coming from the tailpipe. This is known as backfiring and is a common symptom of a bad ignition coil. Backfiring occurs when there’s an insufficient spark for combusting the fuel-air mixture in the cylinders, which results in the combustion of fuel and air in the exhaust system instead. If you are experiencing loud noises coming from your tailpipe, it’s likely time to think about replacing your ignition coil.
Engine Jerking, Rough idling, Poor Power Output

If your vehicle is jerking or running rough when you try to accelerate, it’s likely an ignition coil issue. Poor power output can be caused by a lack of spark due to the faulty coil as well as an engine that isn’t able to combust efficiently. This will also cause the engine to idle roughly at slow speeds and not perform optimally during high-speed driving. All of these symptoms indicate that the ignition coil needs to be replaced in order to restore optimal performance.
Strange Engine Noise
When an ignition coil has gone bad, it can cause strange noises to emit from the engine. This is caused by a lack of spark in the cylinders, resulting in incomplete combustion and poor performance. The noise will likely be similar to a hissing or popping sound coming from under the hood and can indicate that the ignition coil needs to be replaced.
Check Engine Light

In some cases, a faulty ignition coil can cause your vehicle’s check engine light to come on. This is usually accompanied by other visible signs such as misfiring, stalling or backfiring. If your vehicle’s check engine light suddenly appears, it is important to have your vehicle inspected and the ignition coil replaced if necessary.
Decreased Fuel Efficiency

If your car isn’t running as smoothly as it used to, this could be a sign that the coil is failing. Poor fuel efficiency is one of the common signs of an inefficient or faulty ignition coil; if you’re getting fewer miles per gallon than usual, then it’s time to get the ignition system checked out. Additionally, the engine will be louder and increase in temperature more quickly than normal.
Poor Starting Performance

When an ignition coil fails, it can cause a car to take longer to start up or even not start at all. This is because the spark plugs aren’t receiving enough current from the coil; if there’s no current, then the spark plugs won’t spark and the car won’t start. If your vehicle struggles to turn on, or it takes longer than usual for it to start, then you should have the ignition system checked out by a professional.
These are the common symptoms of a bad ignition coil. If you are experiencing any or all of these symptoms, it is important to have your car inspected by a professional and get the coil replaced if necessary. Ignition coils are essential for the safe and efficient running of your vehicle, so it’s important to take care of this issue right away.
Causes of a Bad Ignition Coil
There are several common causes that can lead to a bad ignition coil. Here are the most common reasons:
Vibrations
Ignition coils are secured to a car engine with metal mounting plates and rubber insulators, but over time these can become worn. This results in vibrations which can cause the coil to malfunction or stop working altogether.
Heat Damage
Heat is generated by an ignition coil as it carries high-voltage electricity from the battery to the spark plugs. If the ignition coil is running too hot, it can become brittle and easily break down.
Mechanical Wear
Over time, mechanical wear on the engine can cause a bad ignition coil. This wear can come from corrosion due to moisture or dirt, as well as constant vibrations that can cause friction and strain on the parts.
Clogged Fuel Filter

A clogged fuel filter can cause a bad ignition coil as it prevents the engine from receiving the needed amount of fuel. This can lead to the engine running too hot, which in turn harms the ignition coil.
Poor Electrical Connection
This is a relatively easy one to diagnose and fix. The electrical connection between the coil and the spark plug may become disconnected, or corroded. This will cause a misfire in the engine, as well as cause your vehicle to run rough at idle. Checking for this issue is fairly straightforward – simply inspect any wiring for corrosion or fraying, and if present replaces it.
Insufficient Voltage
Your ignition coil needs a certain amount of voltage to operate correctly. If the voltage supply is too low, or there are issues in the charging system, it can cause your ignition coil to fail. If you suspect this is the issue, check your battery and charging systems first to see if they are working properly.
Faulty Coils
Another common cause of a bad ignition coil is simply that it has gone bad. This can happen due to age or could be due to other issues like overheating. If you suspect this is the case, replace your ignition coil with a new one and see if the issue is fixed.
Incorrect Ignition Timing

If your car’s ignition timing is off, it can cause your ignition coil to fail. The timing of your spark plug firing needs to be in sync with the position of the piston – if this is not the case, it can cause misfires and other issues. If you suspect this is the issue, have your car’s timing checked by a professional mechanic to ensure it’s correct.
Finally, it is important to note that these are the most common causes of a bad ignition coil – however, they are not the only ones. If all other issues have been ruled out and you still have an issue with your coil, contact a professional mechanic for further assistance.
Different Types of Ignition Coils
There are a variety of different types of ignition coils used in modern engines. Ignition coils create the spark necessary for combustion, and their design has evolved over time to provide better performance. Here are some of the most common types of ignition coils used in automobile engines:
Point-style Ignition Coils

Traditional point-style ignition coils are the oldest type of ignition coil, dating back to the early days of automotive engines. Point-style ignition coils have metal contact points that close when an electric current is applied. When the points open, they create a spark that ignites the fuel and air mixture in the engine cylinders. Point-style ignition coils are still used in some older model vehicles, but they have largely been replaced by modern electronic ignition systems.
Distributorless Ignition Systems (DIS)

Distributorless Ignition Systems (DIS), also known as coil-on-plug systems, were introduced in the 1990s. This type of ignition system does not use a distributor but instead uses an individual coil for each spark plug. DIS coils are typically smaller than point-style coils and provide better performance because the spark is delivered directly to the plug, eliminating any potential delays caused by voltage traveling through a distributor.
Coil-On-Plug Ignition Coil (COP)

Coil-on-plug ignition coils are similar to DIS coils, but with one major difference: they mount directly on the spark plug. This eliminates any delay in voltage delivery and provides a more reliable spark for optimal engine performance. COP coils are commonly used in high-performance engines, as well as certain types of hybrid vehicles.
Ignition Coil Packs

Ignition coil packs are a relatively new type of ignition system that combines multiple coils into one compact unit. These coils can be used to fire multiple spark plugs simultaneously, providing better performance and fuel efficiency. Additionally, coil packs are more reliable than point-style or DIS systems, as they don’t require replacing individual coils when they go bad.
High-Energy Ignition (HEI)

High-energy ignition (HEI) systems use a single coil to fire all of the spark plugs in an engine. HEI coils are typically larger than point-style or DIS coils, and they provide higher spark energy for better fuel efficiency and performance. Additionally, HEI coils are more reliable than other coil types because they can provide a consistent spark over a long period of time.
The type of ignition coil you choose will depend on the type of engine and performance requirements you have. Point-style coils are still used in some older vehicles, but DIS, COP, coil packs, and HEI systems are becoming increasingly popular in modern engines. It’s important to do your research and choose the ignition coil that is best suited for your application.
How long do ignition coils last?
Ignition coils are designed to last for a long time, typically around 100,000 miles or more, but their lifespan is still affected by several factors such as heat and vibration.
When there is too much heat or resistance in an ignition coil, it can cause the insulating material inside it to break down and lead to internal failure. Excessive heat and vibration can also wear down materials over time which can reduce the operating life of the coil. Additionally, secondary ignition components like spark plugs and wires that are worn out can increase the demand on the ignition coil since they require more voltage, leading to a shorter lifespan.
When an ignition coil begins to fail, one of its symptoms is poor performance in terms of gas mileage. This happens because it requires more fuel in order for it to function properly, resulting in higher expenses on gas than normal. In order to prevent this issue from occurring regularly, it is important that drivers conduct regular maintenance checks on their vehicles and replace parts when necessary so that they do not have to worry about replacing expensive parts too often due to damage caused by neglecting maintenance checks.
How Much Does it Cost to Replace an Ignition Coil?
Your car’s new ignition coil cost will vary depending on its make and model – some cost as low as $75, while others can range up to $300. If you aren’t able to replace it yourself, hiring a professional could cost anywhere between $50-$100 per hour for labor.
Thus, if you resolve to take your car to an automotive repair shop and have them replace the ignition coil for you, be prepared to pay at least $150-$200. If it’s a dealership service you’re after, then plan ahead for even higher costs.

How To Change Ignition Coils Yourself?
Once you have identified that an ignition coil needs to be changed, there are some steps you can take to safely and effectively replace it.
Step 1: Safety First
Before beginning any automotive repair or maintenance, make sure it is safe to do so. If a vehicle is running, turn off the engine and disconnect the negative battery cable before proceeding.
Step 2: Locate the Ignition Coil
Depending on your vehicle’s make and model, the location of the ignition coil may vary. Common locations include near the spark plug, distributor, intake manifold, or cylinder head.
Step 3: Remove The Old Ignition Coil
Once you have located the ignition coil, you can then remove it from its mount. Start by removing any wiring connected to the coil and then unscrewing it from its bracket using a socket wrench.
Step 4: Test Each Ignition Coil With A Multimeter

To ensure that the ignition coil is faulty, use a multimeter to test each one. You should see resistance measurements of between 1 and 10 ohms for primary resistance and between 4 and 12 kilohms for secondary resistance.
Step 5: Clean and Prepare The New Ignition Coil
Once you have confirmed that the old ignition coil is faulty, prepare the new one for installation. This includes cleaning any dirt and debris from the mounting bracket as well as adding a bit of anti-seize compound to the threads.
Step 6: Install The New Ignition Coil
Now it’s time to install the new ignition coil. Start by connecting the wiring to the coil and then carefully screwing it into place. Make sure to tighten it securely so that it is properly seated.
Step 7: Re-connect The Battery Cable
Before returning your car to normal operating conditions, make sure you reconnect the negative battery cable. This will ensure that all of the components are properly connected and receiving the correct power.
Step 8: Test The Ignition System
Now that the new ignition coil has been installed, you can test it to make sure it is working properly. Start your vehicle and look for any signs of misfiring or chugging. If everything seems to be working properly, you can then put the car back in gear and take it for a test drive.
Step 9: Check The Ignition System Again
After you have taken the car for a test drive, check the ignition system again to make sure everything is running smoothly. If you notice any strange noises or vibrations, make sure to get them checked out as soon as possible.
Taking these steps can help you properly and safely change your ignition coils. Be sure to follow all safety instructions and use the correct tools when working on automotive repairs. Taking the time to research the issue and understand how to properly replace an ignition coil can help ensure that the job is done correctly, saving you time and money in the long run.
How to Test/Diagnose A Faulty Ignition Coil?

If you’re trying to check an ignition coil, whether it be a CNP (Coil-Near-Plug) or COP (Coil-On-Plug), here are a few pointers and tips that may come in handy!
CNP Coil Type
The first step in testing an ignition coil is to shut off the engine and open the hood of your car. It’s important to wear insulated gloves and use insulated tools when handling these electrical components, as you can get a painful shock otherwise.
Take the spark plug wire from the distributor cap, which connects to the spark plug, and attach either a new or old spark plug to the wire.
Use insulated pliers to hold the spark plug against a metal part of the engine so that the threaded portion is in contact with it.
Then, use either a fuse removal tool or needle nose pliers to disconnect the fuel pump fuse and be ready to crank the engine.
It’s helpful if you have a second person to turn the key in the ignition while you hold down the spark plug.
Once the engine is cranked, look for blue sparks between the spark plug gap. If you see these sparks, then your ignition coil is working properly.
However, if no sparks are seen or orange sparks are present, this indicates that your coil is malfunctioning.
Finally, after the test is complete, disconnect the spark plug and put it back in its hole.
Reconnect the spark plug wires to it, and then replace the fuel pump fuse.
Now that you know how to test an ignition coil, you can determine if your car’s ignition coil is working correctly.
COP Coil Type
Testing an ignition coil is a relatively straightforward process, but one that requires special attention to detail. To test an ignition coil of the COP (coil-on-plug) type, start the engine and bring it to its idle speed. Once the engine is running, open up the first ignition coil bolt, and slowly pull the coil away from its seat. If the engine’s running condition changes to become more rough or uneven, then this means that the first ignition coil is functioning correctly. Continue testing each of the remaining coils in sequence until you locate the faulty one – when a faulty coil is pulled out, there should be no noticeable difference in engine performance.
Once the faulty coil has been identified, it can be replaced. This will help to ensure the optimal functioning of your engine and allow it to perform at its best.
Keeping it in good condition is essential for a properly functioning engine, so make sure to run this test any time your car starts having trouble starting or running. If necessary, you can then replace the faulty ignition coil and get back on the road.
Q: What should I look for when purchasing replacement ignition coils?
When replacing your ignition coils, it’s important to make sure you purchase the correct type for your vehicle. Check with your car’s manufacturer or consult a qualified mechanic before making a purchase so that you get the right fit and quality of the product. Additionally, be sure to check the warranty on any new parts you buy to ensure they are covered in case of premature failure.
Q: Are there any preventative measures I can take to avoid replacing my ignition coils?
To minimize the risk of needing to replace your ignition coils prematurely, it’s important to follow regular maintenance schedules as directed by your vehicle’s manufacturer. Additionally, if you experience any signs that suggest a faulty ignition coil such as difficulty starting the engine or trouble with acceleration, have them inspected immediately so that any necessary repairs are done before further damage is caused.
Q: Is replacing bad ignition coils a DIY job?
While you can do basic maintenance on your vehicle yourself such as changing the oil and checking fluids, replacing bad ignition coils is something that should only be done by a qualified mechanic. Not only do they have the necessary tools and expertise for this type of work, but also having the right parts properly installed is critical to ensure the proper operation of your vehicle. If you attempt to replace the ignition coils yourself without having them professionally checked and proper potential replacement parts correctly installed and proper installation carried out, you may end up with the same problem again down the road. Therefore, it’s best to leave this job to a qualified mechanic instead of attempting it yourself.
Q: What happens if I don’t replace bad ignition coils?
If you ignore signs that indicate an issue with your ignition coils such as difficulty starting or reduced fuel efficiency, not only will these issues persist but could also lead to more serious problems in the future. If left unchecked, the damaged ignition coils could cause further damage to the engine and result in a costly repair bill down the road. Therefore, it’s important to have any suspected bad ignition coil issues professionally inspected and replace them as soon as possible so that your vehicle does not develop any additional or more expensive problems.
Wrapping Up
Overall, an ignition coil is a vital part of your car’s ignition system and can be the cause of many issues. Without proper maintenance and replacement when needed, a bad ignition coil can lead to significant damage to other parts of the engine and ultimately render your vehicle unusable. When it comes to the cost of replacing an ignition coil, it typically ranges from $150-$200 depending on the make and model of your car.
Additionally, it’s always best to consult a certified mechanic for help in identifying any signs or symptoms that may point to an issue with your vehicle’s ignition coil. Following these simple steps can ensure that you remain on top of any potential problems with your vehicle’s ignition system, ensuring safe and reliable operation moving forward.