What causes ignition coils to keep going bad | 6 Symptoms Discussed

the 6 causes ignition coils to keep going bad

The ignition coil is a significant part of any vehicle’s ignition system. It mainly provides the required voltage for creating the spark and kickstart engine.

As a result, without a doubt, it becomes a vital part of turning the car on and has to be taken care of. The best way to keep an ignition coil from becoming a lousy one is to keep your spark plugs in the best possible condition.

But for many reasons, it can go bad and malfunction. It can lead your vehicle’s ignition system to fail and cause significant damage to the parts.

What causes ignition coils to keep going bad

So, what causes Ignition Coils to keep going bad? There are several reasons for ignition coils keep going bad. Here I am discussing these.

Worn or damaged spark plugs

Damaged spark plugs force the ignition coils to function at a much higher output, putting strain on the coils. The gap in which each spark plug is fired increases as the spark plugs wear down. Hence, the coil needs to provide a higher voltage to cover the gap. Thus, the additional strain on the coil can cause voltage overload, followed by overheating and eventually failure.


Heat increases the resistance throughout the coils, and because of this high resistance, electricity can not pass through. As the coil could not conduct electricity, the ignition coil failed to function.

Wear and tear

It is a principal reason for ignition coil failure. The insulation between primary and secondary coil windings and primary coil degrades. This degradation eventually leads to overheating and causing the ignition coils to malfunction.


Ignition coil windings and insulation can get damaged by vibration. It leads to shorts or breaks in the secondary windings of the ignition coil.

Battery power supply

The power supplied to the ignition coils plays a crucial role. If the battery power supply is unstable, it can cause the ignition coil to burn out and stop functioning.

Vehicle computing system

The computing system can show a failure signal because of a short circuit in the vehicle. The probable cause is a failing ignition coil. Hence, you should take the car for service as soon as possible.

symptoms of a bad ignition coil

The first thing you need to check for is the Engine Check Sign, if that is lit – scan the error code. If the error code is in the range of P0300-P0312, that stands for engine misfire, however some vehicles are capable of giving a further indication, and they might provide an erro code in the range of P0350-P0362, this signifies that you have a bad ignition coil.

Here is a list of Symptoms of a bad ignition coil:-

  • Unwanted Vibrations
  • Loss of Power
  • Engine Light
  • Rough Idle
  • Smell of gas or other foul smell
  • lower than average fuel economy

how long do ignition coil packs last?

How Long Do Ignition Coil Packs Last

An ignition coil’s lifetime depends on its usage and surroundings even. For example: If the spark plug is old or unable to function correctly, the ignition coil will not work.

Usually, an ignition coil can last around 100,000 miles even more if all the parts are working well and no cause to harm the ignition coil.

At present, technologically advanced cars and the latest ones have a layer of protection like rigid plastic insulation for protecting the coil.

The ignition coils have copper wires inside, which get damaged over time due to heat, moisture, etc. If the wires are okay and not damaged, the overall performance will be up to the mark.

Ignition coil insulation method

Plastic molding type (referred to as PP plastic molding)

After the initial assembly, the coil is saturated with varnish for a specific time. Later on, the coil is left to dry and harden before taking it out. The inside of the coil is insulated using varnish filled. Finally, the coil gets a plastic mold covering the entire outer body.

Asphalt-filled type

Initially, the coil is put inside a metal casing, and it is filled with asphalt surrounding the coil to cover it entirely. In the case of insulation, this method is the earliest for making automotive ignition coils.

Oil-filled type

Like the previously mentioned method, here, instead of asphalt, oil is used as the insulating layer. It has impressive permeability and insulation resistance. However, the oil, namely Polychlorinated Biphenyl, is poisonous. Hence, it is risky to handle and universally banned.

Epoxy resin-filled type

The coil is placed inside a resinous case, and then it is filled with epoxy resin to use as an insulation material. The materials required to manufacture ignition coils using this type of insulation are readily available. Hence, Epoxy resin-filled ignition has become the mainstream of ignition coils for both motorcycles and automobiles.

How can I tell which ignition coil keeps going bad?

Which Ignition Coil Keeps Going Bad

Ignition coil packs are, nowadays, many in the market. It might get confusing to choose or detect which one is bad or won’t work correctly. You can detect the lousy coil pack by some visible signs.

  • There are some signs in the initial stage that you can look for. You can check the coil pack for any detectable burn marks, cracks, corrosion carbon tracking. The coil’s housing can also have oil leaks, so; it would be best to inspect the housing and system’s wire.
  • Any bag ignition coil pack can cause a rough idling engine. It is a big deal as it can cause massive damage to your engine, even allowing it not to run.
  • Your engine can get a bit louder compared to regular. This more audible engine can be a sign of the lousy ignition wires.
  • You can also notice that the power is lessened than in the initial stage. The bad ignition coil might be its reason.
  • The car’s RPM or revolution per minute has decreased by a lot over time. A bad ignition coil pack usually causes this problem.
  • The “check engine” signal might start blinking or get activated intermittently instead of slowly illuminating. This sign can be a problem caused by a bad coil pack.

Can a bad ignition coil cause transmission problems?

Can A Bad Ignition Coil Cause Transmission Problems

In the case of old model cars, shifting depends on the engine vacuum. When the engine misfires because of a malfunctioning ignition coil, the void in the intake manifold reduces and provides incorrect load information to the transmission vacuum modulator.

Hence, the shifting is delayed and happens harshly. The transmission will be affected only to this extent because of a defective ignition coil.

However, damage to the engine is more probable than the transmission if the issue is not fixed.

Frequently Asked Questions

#1. Why Does My Ignition Coil Keep Burning Out?

A large gap between the spark plugs can cause the coil to overheat and short circuit. Then again, if the battery power supply provides unstable power, the ignition coil may burn out.

The vehicle computing system can show a failure signal indicating a possible short circuit in the system, which is probably a malfunction in the ignition coil.

#2. What Causes Multiple Ignition Coils To Fail?

In case of repeated coil failures, it may be that the coils are functioning too hard than necessary. It can happen because of high secondary resistance.

This increased resistance is usually caused by a damaged or worn-out spark plug or too much gap between the plugs.

#3. Why Does My Car Keep Blowing Coil Packs?

One of the principal reasons is because of the old age of your car. Apart from this, super high voltage can blow up coil packs too.

When the super high voltage is built up inside the coil it fails to find any ground through the distributor cap, rotors, it could blow up. Hence, keeping the components in tip-top shape is very crucial.

#4. What Are The Signs Of A Bad Ignition Coil?

Here are some signs that indicate your ignition coil is bad.
– Vehicle backfiring
– Vehicle stalling
– Poor fuel economy
– Problems starting the vehicle
– Engine misfiring
– Jerky engine, rough idling with insufficient power
– Engine hard starting
– ‘Check engine’ light on

#5. How Can You Tell If An Ignition Coil Is Bad?

While inspecting the ignition coil, the coil has gone bad if there are any visible burn marks, corrosion, wear, and tear. In case of damage not visible to naked eyes, you can use an ohmmeter to find resistance across the coil to see if it is too high or not.

There are also tools like COP probe and oscilloscope available in the market for a more thorough inspection.

#6. Can You Drive With A Bad Ignition Coil?

The better answer to this is, “Should you drive with a bad ignition coil?” It is not advised because the faulty ignition coil will affect other components of the car.

Eventually, the entire system can break down. Hence, it would help if you repaired the defective ignition coil within a week before it starts affecting any other parts of the car.

#7. Should I Replace All Ignition Coils At Once?

You should not because one coil pack is used for two engine cylinders, and you should only change the faulty one. Either the coil pack functions or does not; there is nothing in between.

Hence, one defective coil pack does not affect the other working ones. On the contrary, Old coil packs in working condition are more reliable than the unopened, brand new ones.  

#8. Have replaced spark plugs and ignition coils but still engine light comes up – why ?

If you have tried everything and still engine light comes up, in some vehicles specally variants of ford, the main computer might need to be reprogrammed to get rid of the engine light re-appearing after part replacement. If this be the case, just other symptoms like air conditioner compressor shutting down. Not many dealers or mechanics would understand or know how to reprogram the main computer. Although it might be a bit expensive, but better to check in with an authorized ford dealer who is skilled to reprogram the main computer. Please don’t rely on the dealer who suggests that you need to replace the main computer or nothing can be done without double checking.

#9 Symptoms are identical for bad pump and bad coils, Is there any symptom specific to a bad coil?

Unfortunately, no, however there are ways you can zero in on whether it is a bad coil or a spark plug. If you have recently replaced a spark plug chances are its a coil, try switching the coils to see if the that moves the error from one place to another on the scanner, if it does chances are its the bad coil.


The ignition coil is crucial for a car to function. Even though there can be some minor problems, they can be resolved relatively quickly if addressed at the right time. In the end, with ignition coil problems, there is nothing to be afraid of nowadays.

The parts required for repair are pretty easily available in the market at an affordable price. I hope “What Causes Ignition Coils To Keep Going Bad” will help to find out the reasons 

This Post Has 10 Comments

  1. PJ

    This was a thorough, superb, easy to understand, article on ignition coils. 3 weeks after our 2019 Ford 150 eco boost warranty expired, one coil failed. Only 28,200 miles and we pull a travel trailer a couple months per year. We love our truck, but disappointed about the costly repair.

  2. Matthew Price

    I have a 2013 chevy express 3500 6.0l, flex fuel … I have never ran flex fuel in the van, I recently had complete tune up done @ a reputable service garage, new wires. Plugs, and cylinder 2 coil pack , according to diagnostic , was misfiring , cause typical issues,, drove the van a few months, started running rough again , I bought my own diagnostic tester. And again, cylinder 2 voil pack was bad, I replaced it , runs great again ,, this is the 2nd coil pack on the same cylinder. I’m assuming this is what possibly happened a couple years ago when I had a complete tune up done as this happened af that time as well…. so, basically, I’m scratching my head as to what would be the underlying issue causing the same cylinder coil pack to malfunction. Please advise if possible.

    Thank you,

  3. Dovy

    I cannot find a mechanic that can help us with this issue on my Ford F-150. Almost $2,000. dollars later and over 3 months sitting in drive way on the second comeback. Do you know of any mechanics willing to work on a truck over 15 years old?

    1. admin

      Where are you based, I would suggest reaching out the ford community forum, they would defintely be able to recommend someone.

  4. Willie Austin

    Well, great post, Dencan!

    Very complete and helpful!

    But I have a question: My car has 8 ignition coils. Should I change all coils or just a bad one?

    My car is a 2013 Civic.


    1. admin

      Just the bad ones. Usually ignition coils will survive the car’s lifetime, so no need to change unless they went bad. Check with your mechanic too what they are suggesting, and see if their suggestion makes sense.

      1. Willie Austin

        Thanks a lot.

      2. Willie Austin

        Hi Admin,

        Btw, I had a suggestion for your blog post, and I tried to contact you via the contact page a week ago.

        Just wondering if you had a chance to take a look at it.

        Please share your thoughts.

        Have a nice day!

        1. admin

          Hi Willie, could you please reshare the suggestion in the comment box here. I couldn’t find the data from the contact forms.

          1. Willie Austin

            Hi Admin,

            After reading through this post, I’ve just tried to put together an infographic about Bad ignition coil symptoms. I’d love to share it with you (totally FREE, of course).

            Would you be interested in checking it out? 

            Let me know, and I can send you the infographic to take a look at.

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