bad ignition coil symptoms

Bad Ignition Coil Symptoms And How To Replace That Faulty Coil

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Today we’d like to talk to you about bad ignition coil symptoms

Do you remember there was this scene in the Big Bang Theory when Penny’s check engine light won’t stop flashing, and it was driving everyone crazy except for her? Should she be worried? Maybe, was it a sign that her car’s ignition coil is going bad?

Maybe, it could be a lot of things, but that should be a good place to start. After all, it’s important that we are up to date of what’s going on with our automobile’s condition, most importantly so with the engine, the heart of any vehicle.

Let’s dive right in and discuss bad ignition coil symptoms, or that check engine light won’t stop bothering you as well. 

ignition coil problemsFirst of all, just a little bit about the basics.

What is an ignition coil?

The ignition coil is an induction coil and an integral part of your automobile’s ignition system that transforms the battery’s low (12 V) voltage to thousands of voltage (15,000 to 20,000 V) needed to ignite fuel.

It creates an electric spark in the sparks plugs in order to do so.

In short, it is a transformer, its function is to step up the voltage.

Bad Ignition Coil Symptoms

Check Engine Light

Where to start but in the most obvious of indications. Once the check engine light is on as what we mentioned in the introduction, you got to check your engine!

One or more misfiring cylinder is a reason why your check engine light is flashing and most for of the time it’s because of a faulty ignition coil.

TIP: While the engine is running, run a scan tool to confirm if a cylinder is indeed misfiring. Next, use a test light and check for spark.

Low Power

A faulty ignition coil will naturally won’t give enough power to the spark plug resulting to weak or no spark at all. This should also be a telltale sign of an ignition coil problem.

Also, ignition coil problems may result in misfires, rough idle, loss in acceleration, reduction in gas mileage or just a total loss of power.

This could also result in your vehicle stalling, which is caused by irregular sparks sent to the spark plugs.

Also, check for cracks as on your coil as excessive heat and ground can cause ignition coil problems. Also backfiring is a symptom of an early stage ignition coil failure.

A car backfiring commonly occurs when the unused fuel in the cylinders of the engine exits through the exhaust pipes.

This is commonly detected by the emission of black smoke, with a smell of gasoline that indicates and ignition coil failure.

With left untreated and unchecked for a long time, it may result in expensive repairs, one that we ought to avoid.

High Mileage

As they say, all good things come to an end, the same as with your ignition coil.

An ignition coil can go for about 60,000 to about 120,000 miles if yours have higher mileage it may be time to replace it. Better to be safe than sorry. It pays to be ready at all times.

Poor fuel economy is also a bad coil symptom. This is when your vehicle is getting significantly less mileage than ever before. You are almost certain that and ignition coil is failing.

Fouled ignition coil

Engine oil contamination may cause an ignition coil to prematurely fail.

This can be brought about a bad valve cover or a bad spark tube that allows engine oil to seep into the spark plug and in time fouls the ignition coil.

Make sure to check up on these components and replace (valve cover) when necessary. Sometimes wiping an ignition coil might help.

External factors

We use our car every day and needless to say it goes through a lot. It has to deal with a lot of elements just so we don’t need to.

Sometimes on tough weather conditions, we drive through flooded roads and at the same time flooding our engine. Water can prevent the ignition coil from working properly when your engine is often soaking wet.

Also, consider animals. Yep, as widely knows some animals especially rats lurk and feast on your engine components.

They sometimes chew on a lot of stuff and your ignition coil wires might be a victim. So try to watch out for these signs and also don’t forget about the rat droppings, it’s not only a sign of rat infestation but could also do harm to your engine in general.

Car not starting AT ALL

When a vehicle is hard to start or is not starting at all then most likely it’s an engine problem, right? So yeah, this is what we call a no spark no start condition.

For vehicles that use a single ignition coil for the sparks on their cylinder, a faulty coil is definitely going to affect your engine’s operation.

New spark plugs are in order

Sometimes our ignition coil is just forced to work harder than it should be. Especially if it has been working awfully hard for a long time because of a faulty spark plug it can go bad.

So don’t just check your ignition coil, check your spark plugs regularly too as clearly one’s performance affects the other, they work hand in hand.

Ignition Coil Replacement Cost

We’ll discuss ignition coil replacement costs briefly in this section.

faulty ignition coilFirst how much does an ignition coil cost?

Well depends on the model of your car it can range from $75 to $300. Also, if you get a pro to do the replacement for you then it will cost you an extra $50 to $100 bucks.

Automotive repair shops and dealerships would naturally cost you more, about $200 more at most.

But if you’re the DIY (Do It Yourself) type or you know your engine you may opt to replace it yourself. We’ll give you some idea on how to replace your faulty ignition coil up next!

How To Replace Ignition Coil

Here’s a DIY guide for replacing your ignition coil.

Now that we know how to detect a faulty coil then let’s dive right into how to replace it after you’ve secured a new one from your local auto shop.

  1. Disconnect your battery’s negative terminal

    Simply enough use a wrench or socket to loosen the bolt for your battery’s negative terminal.

    Then, make sure to securely tuck it in place to make sure it won’t come in contact with the terminal. We don’t want you to accidentally get shocked, no sir.

  2. Locate the culprit!

    Locate the faulty ignition coil. This can be done through specific different ways, an ignition spark tester, and OBD-II code scanner or using an application-specific repair manual that can be bought in auto-parts stores or online.

  3. Unplug the wires

    Unplug any cable harnessing your ignition coil. There may only be one or more that you need to unplug.

    A tip though is to make sure to pull on the cables hard and only pull on the lower part of the boot to not damage the internal wiring.

    Again like the earlier, tuck the cables properly. Remove remaining bolts accordingly.

    TIP: Label the spark plug cables accordingly for ease of identification.
  4. Out with the old, in with the new

    Easy enough, after removing the old coil, a quick comparison with the new one should follow for obvious reasons. It could save you a lot of time dealing with the hassle of an incorrect coil later on.

    Put new coil in place, the same orientation as the old one, it won’t fit in any other way anyway. And insert the bolts and hold the coil in its proper place.

    Connect plug for the ignition coil, plug all the cables back in (You labeled them? Great!). Wait for the pop to make sure they are properly mounted.

  5. Get Greasy

    Apply dielectric grease to help keep water out of the connection and to prevent the boot from sticking to the spark plug.

    Proceed and replace some other coil packs.

  6. Start your car! Test drive time!

Best Rated Ignition Coil Brands

Some of the best brands out there are as follows:

  • ENA Auto Parts (ENAIC1115108) – ignition coil set
  • Bosch (00044) – best ignition coil for BMW
  • ENA Auto Parts (ENAIC115401) – straight boot ignition coil
  • ECCPP (ECCPP070573) – Good aftermarket ignition coil
  • QYL (154293) – best ignition coils for KIA and Hyundai
  • Parts Galaxy (IC101k) – ignition coil set
  • King Auto Part (DG508YELLOW) – complete set

Bad Coil Symptoms – Conclusion

So did Penny ever got around to get her engine checked? I don’t know, maybe she just got rid of the car altogether.

But you shouldn’t have to. Armed with knowledge only from, we’re confident that you know what to do!

Bad ignition coil symptoms should not be ignored to prevent further damage to your automobile. It saves you time, energy, and money, cha-ching!


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