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What Causes Ignition Coils to Keep Going Bad? - Southwest Performance Parts

What Causes Ignition Coils to Keep Going Bad?

Wondering what causes ignition coils to keep going bad? From simple age & wear to problems with overheating, improper installation, and other problems with the fuel pump or spark plugs - the causes of bad ignition coils are seemingly endless. This makes it tough to nail down the root cause of your problem. And when you have to replace coils more than once, it really starts to get frustrating.

That’s why we’ve put together this comprehensive list of what causes ignition coils to go bad. We’re also going to share some of the ways you can prevent premature ignition coil failure and extend the life of your coils. But first, let’s cover some of the most telltale bad ignition coil symptoms so you can spot the problem in the first place

Bad Ignition Coil Symptoms: Signs Your Coils are Going Bad

Before we get into what causes ignition coils to keep going bad, we want to provide you with a list of bad ignition coil symptoms. This will help you identify a problem early on and potentially save you more costly headaches down the road.

  • Engine misfires: One of the most common symptoms of a bad ignition coil is engine misfires. Misfires occur when the spark plug doesn't ignite the fuel-air mixture in the cylinder, which can cause the engine to shake or vibrate. This can throw the check engine light on as the ECU (engine control unit) detects misfires or other issues related to the ignition system.
  • Rough idling: A failing ignition coil can cause the engine to idle roughly, with the engine speed fluctuating and the vehicle shaking. If you drive your car often enough, this is a change you’ll likely notice when you stop at a red light after the car has warmed up a bit. 
  • Reduced power and acceleration: A failing ignition coil can also cause reduced power and acceleration as the engine struggles to maintain speed. If you find it harder to get up to speed on the freeway or as if you’re fighting to get your car into the next gear, this could be why.
  • Stalling: In some cases, a bad ignition coil can cause the engine to stall, particularly when idling or at low speeds. At this point, the ignition coil has completely failed and needs to be replaced.
  • Poor fuel economy: A malfunctioning ignition coil can cause poor fuel economy, as the engine struggles to burn fuel efficiently. This is another reason why tracking your MPG is so crucial - you can spot signs like this easily.
  • Backfiring: A bad ignition coil can cause backfiring, which is not to be confused with misfiring. This occurs when the fuel-air mixture in the cylinder doesn't ignite correctly, causing a loud explosion in the exhaust system.
  • Hard starting: A failing ignition coil can make it difficult to start the engine, especially in cold weather.
  • Increased emissions: A bad ignition coil can cause increased emissions, as the engine struggles to burn fuel efficiently, which can lead to the failure of the catalytic converter.

If you're experiencing any of these symptoms, it's important to have your ignition system checked by a professional mechanic. Ignoring the problem can lead to more serious issues and can even cause damage to other engine components. 

Additionally, if you have an older vehicle or if your vehicle has high mileage, it's a good idea to have your ignition system inspected as part of regular maintenance to prevent problems before they occur. With that said, let’s take a look at what causes ignition coils to go bad - since that’s what you came here for in the first place!

What Causes Ignition Coils to Keep Going Bad?

Now, you’ve identified that something isn’t right - and narrowed it down to the ignition coils. But what causes ignition coils to keep going bad? Why are you dealing with this issue? We’ll highlight the 10 common culprits below to help you diagnose the problem and put an end to this frustrating occurrence once and for all. Let’s start by ruling out simple age & wear. 

Simple Age & Wear

Over time, ignition coils can wear out and become less efficient. This is particularly true if they are subjected to extreme temperatures or environmental conditions. 

Symptoms of aging or worn ignition coils include misfires, rough idling, and decreased fuel economy. A simple way to test the condition of an ignition coil is to measure its primary and secondary resistance with an ohmmeter. Consult your car's repair manual for the acceptable range of resistance values and take a look at the readings to see if something is amiss.


Ignition coils can overheat if they are forced to work too hard. This can happen if the spark plugs are worn, there is a problem with the fuel injectors, or the engine is running too lean. 

Beyond watching your temp gauge on the dash, you can tell your car is overheating if you experience engine misfires and/or a rough-running engine. To diagnose this issue, you'll need to inspect the spark plugs, fuel injectors, and fuel system for any problems.


Your car’s engine is a dirty place - there are all sorts of fluids like oil, grease, coolant, etc. And, when you hit the open road, dirt & debris can make their way into the engine bay - even if you have a solid filter. As such, there is always a risk of contamination at the spark plugs, which can lead to failure. 

Symptoms of contamination include engine misfires, rough idling, and decreased fuel economy. The good news is that diagnosing this issue is easy. Simply inspect the ignition coils for any signs of contamination, such as dirt or debris. You can wipe them clean before it's too late. We also encourage you to prevent them from getting dirty in the first place by keeping your engine bay clean and addressing leaks/spills fast.

Electrical Problems

Electrical problems such as a faulty wiring harness, corroded connectors, or a weak battery can cause ignition coil failure. This cause of bad ignition coils has many of the same symptoms we’ve already discussed - engine misfires and a rough running engine. 

To diagnose this issue, inspect the wiring harness and connectors for any signs of damage or corrosion. Check the battery voltage with a multimeter and ensure it's within the manufacturer's recommended range.

Improper Installation

We’ve all tried to do DIY projects before that we may not have been qualified for. And while changing the ignition coils isn’t the most complex automotive repair, improper installation is still one of the leading causes of premature ignition coil failure. This can be the result of using the wrong coils altogether or skipping over a step on accident. 

If you suspect this could be the culprit behind your failed ignition coils, we encourage you to just take the car into a shop and let the professionals handle it. It’s worth the money to enjoy peace of mind!

Incorrect Voltage

If the voltage supplied to the ignition coil is incorrect, it can cause the coil to fail. One way to differentiate this from other causes is to measure the voltage supplied to the ignition coil and ensure it's within the manufacturer's recommended range. If the voltage is too high or too low, this may be causing the problem.

Mechanical Damage

Obviously, a cracked or otherwise damaged ignition coil is not going to work as intended. This can result from excessive vibration or a fender bender. It’s also possible that the coils arrived broken and were installed that way if proper care wasn’t taken. So - inspect the coils visually and rule out any signs of damage. 

Spark Plug Problems

A lot of issues you experience with your vehicle can result in issues elsewhere. One example of this is a bad serpentine belt leading to issues with the power steering system or alternator. Similarly, bad spark plugs can cause premature failure of the ignition coils. So always inspect the spark plugs when attempting to diagnose what causes ignition coils to keep going bad. There’s a chance it has nothing to do with the ignition coil itself.

Fuel System Problems

Similarly, problems with the fuel system, such as a clogged fuel filter or a malfunctioning fuel pump, can cause the engine to run lean or rich, which can lead to ignition coil failure. One way to differentiate this from other causes is to inspect the fuel system for any problems and perform a fuel pressure test. If the fuel system is not providing the correct amount of fuel, this may be causing the problem.

Environmental Factors

Extreme temperatures, moisture, and exposure to corrosive substances can all contribute to ignition coil failure. These are unpreventable to a certain extent depending on where you live - such as the hot desert or the freezing tundra. Or, maybe you live near the ocean and salt contaminates your coils earlier than you’d like. Either way, you may not have much choice other than to replace coils more frequently.

Tips for Prolonging the Life of Your Ignition Coils 

Knowing what causes ignition coils to keep going bad, you can then take your diagnosis and correct the issue going forward. This may be something you can do yourself, or you may need to schedule an appointment at a shop near you depending on the scope of the job.

But at any rate, we want to leave you with a few tips for prolonging the life of your ignition coils going forward. No matter what causes ignition coils to go bad in your unique circumstances, you can benefit from following this advice:

  • Regular maintenance: One of the best ways to prolong the life of your ignition coils is by following your car manufacturer's recommended maintenance schedule. This includes regular tune-ups, replacing spark plugs, and checking the ignition system for any signs of wear or damage.
  • Keep the engine clean: A clean engine runs cooler, which can help prevent ignition coils from overheating. Regularly cleaning your engine and keeping it free of dirt, grime, and debris can also help prevent contamination of the ignition coils. This is something you can do yourself a few times a year and it’ll pay huge dividends not just in performance - but engine bay appearance too!
  • Replace spark plugs on time: Worn or fouled spark plugs can cause the ignition coils to work harder, leading to premature failure. Make sure to replace your spark plugs at the recommended intervals to prevent this from happening.
  • Use high-quality ignition coils: When replacing ignition coils, it's important to use high-quality, OEM (original equipment manufacturer) parts. Cheaper aftermarket parts may not perform as well and can lead to premature failure. For the best high-performance ignition coils, you can count on Southwest Performance Parts. We offer the best of both worlds in terms of reliable, quality auto parts that don’t break the bank. We even have LS ignition coils!
  • Check the battery: A weak or failing battery can put extra strain on the ignition coils, leading to premature failure. Regularly check your battery's voltage and replace it if necessary.
  • Keep the engine well-tuned: A well-tuned engine runs more efficiently, which can reduce the workload on the ignition coils. Make sure your engine is properly tuned and any issues are addressed promptly.
  • Avoid extreme temperatures: Extreme heat or cold can cause ignition coils to fail prematurely. If possible, park your car in a covered area and avoid driving in extreme temperatures. If your car is extremely hot, try not to push it further with hard accelerations.

Parting Thoughts on What Causes Ignition Coils to Keep Going Bad

There you have it - what causes ignition coils to keep going bad? It can be any number of things as you now know. Dealing with this problem once is frustrating - but having to continually replace your ignition coils will have your blood boiling. Hopefully, you can take the information we’ve laid out in this guide and address the root cause of your ignition coil woes - preventing future headaches. 

So, what are you waiting for? Get to work diagnosing what causes ignition coils to go bad so frequently in your vehicle. Then, head over to our shop and get the performance ignition coils you need for peace of mind and high performance in your car. We have all the other parts you may need to restore or enhance your car, too - including high-performance transmission coolers, performance headlights, performance brake boosters, performance fuel pumps, and a whole lot more.

Explore the full catalog today. You’ll be glad you went with Southwest Performance Parts! 

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