5 Symptoms of a Bad Ignition Coil in Your Vehicle

An ignition coil in a vehicle basically serves as a compact electrical transformer. In other words, an ignition coil has the ability to convert the 12-volt electrical current from a car battery into at least 15,000 volts of electricity for the spark plug.

This high-voltage current gets sent to the spark plug and then the spark plug is able to ignite the fuel so that the engine can start up.

There is one ignition coil for each spark plug. In some vehicles, the spark plug and ignition coil are connected together with wires, while other cars will just have the ignition coil positioned above the spark plug without the need for wires.

Either way, you need good ignition coils in order to ensure the engine starts up fine. Otherwise, having a faulty ignition coil will make your vehicle susceptible to misfires and cause an increase in the amount of fuel being consumed.

Related: Common Symptoms of Faulty Spark Plugs

Top 5 Bad Ignition Coil Symptoms

If you are experiencing any driving problems related to the combustion process in the engine, you could possibly have a bad ignition coil. The exact symptoms are dependent on how bad the condition of the ignition coil actually is.

Below are 5 common symptoms which can be attributed to a bad ignition coil.

1) Stalling

If your vehicle begins to stall as you’re driving, it could be related to your ignition coil being bad. Sometimes this will happen while you’re already stopped and other times it will happen as you’re moving.

If the coil is just starting to go bad, it will send irregular electrical currents to the spark plug. That is why you could be driving normally and then suddenly experience problems later.

Once you are moving and the stalling starts, it will eventually lead to you stopping completely and not being able to start back up.

2) Engine Misfiring

If you try to start your engine up and you hear a spluttering sound repeatedly, then you are likely experiencing an engine misfire that can be attributed to a bad ignition coil.

You may still be able to drive your vehicle, but you will hear a lot of strange noises and even feel jerkiness as you accelerate the vehicle.

3) Bad Fuel Economy

When there is a bad ignition coil and there are engine misfires because of it, then an increase in fuel consumption is likely going to follow.

As a result, you will have reduced mileage from your gas tank and you will need to fill up your tank more often. This means you will be spending a lot more money on gas than you normally did before.

4) Backfiring

At the beginning of having ignition coil problems, your vehicle will experience a backfiring problem. This is a term that refers to a situation where the internal combustion cylinders have unused fuel left in them and it ends up flowing out of the exhaust pipe.

The first sign of this will be black smoke pouring out of the exhaust pipe. This smoke will have a gasoline smell to it as well.

5) Check Engine Light

Since a bad ignition coil directly affects the functionality of the engine, then you can expect the check engine light to illuminate on your dashboard. There are even some vehicles out there which only have one ignition coil and spark plug.

So, without at least one working ignition coil, the cranking of the engine will occur when there are no sparks being generated inside the cylinders. Of course, a check engine light can mean any number of things wrong with your vehicle.

But if you have experienced any of the previous four symptoms listed above and then you have a check engine light on too, then the ignition coil is likely to blame.

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