Skip the auto shop - Our mechanics make house calls
  1. Home
  2. Articles
  3. Symptoms of a Bad or Failing Ignition Coil

Symptoms of a Bad or Failing Ignition Coil

ignition cable

Ignition coils are an electronic engine management component that are a part of the vehicle’s ignition system. The ignition coil functions as an induction coil that converts the vehicle’s 12 volts into the several thousand that are required to jump the spark plug gap and ignite the engine’s air-fuel mixture. Some ignition systems will use one coil to provide the spark for all of the cylinders, however most newer designs use an individual coil for each cylinder.

As the ignition coil is the component responsible for generating the engine spark, any problems with it can quickly lead to engine performance issues. Usually a faulty ignition coil will produce a few symptoms that alert the driver of a potential issue.

1. Engine misfires, rough idle, and loss of power

One of the most common symptoms associated with a faulty ignition coil is engine performance issues. As the ignition coils are among the ignition system's most vital components, an issue can cause spark to be compromised, which can quickly lead to performance issues. Faulty coils may cause the vehicle to experience misfires, a rough idle, a loss in power and acceleration, and a reduction in gas mileage. In some cases the performance issues may even result in the vehicle stalling.

2. Check Engine Light comes on

Another symptom of a potential issue with the vehicle’s ignition coils is an illuminated Check Engine Light. Faulty coils can lead to engine performance issues, particularly misfires, which will trip the computer and set off the Check Engine Light. The Check Engine Light will also be set off if the computer detects an issue with the ignition coil signal or circuit, such as when a coil burns out or shorts. An illuminated Check Engine Light can be caused by a wide variety of issues, so having the computer (scanned for trouble codes)[] is highly recommended.

3. Car is not starting

A faulty ignition coil can also lead to a no-start condition. For vehicles that use a single ignition coil as the source of spark for all of the cylinders, a faulty coil will affect the operation of the entire engine. If the coil fails completely, it will leave the engine without spark, which will result in a no spark, no-start condition.

Problems with ignition coils are usually easy to detect as they produce symptoms that will be quite noticeable to the driver. If you suspect that your vehicle’s ignition coils are having an issue, have the vehicle inspected by a professional technician from YourMechanic to determine if any coils need to be replaced.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Still not sure about your car's issue?
Diagnose your car
What kind of issue are you experiencing?
Brakes are squeaking
Car is not starting
Car is overheating
Car is shaking (vibrating)
Fluids are leaking
Heating and A/C
Smoke or steam is coming out of the car
Warning light is on

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.


More related articles

Veteran and Military Driver Laws and Benefits in Idaho
The state of Idaho offers a number of benefits and perks for those Americans who have either served in an Armed Forces branch in the...
Veteran and Military Driver Laws and Benefits in New Mexico
The state of New Mexico offers a number of benefits and perks for those Americans who have either served in an Armed Forces branch...
Auto Safety Tips
Driving is more than a way to get from point A to point B. Owning and driving a car can also be a highly enjoyable experience. Whether a person is driving...

Related questions

Q: What could cause my ESP light and ETC light to come on while driving?

The ETC is your electronic throttle control which is usually related to a low voltage problem. Start by having the voltage to the unit checked. The ESP light is the electronic stability light which can also have problems when there...

Q: Misfire - 2002 Mitsubishi Eclipse

Hey there. These two codes are most likely related as an intake air leak can cause a misfire due to the lean fuel condition it creates. When there are no intake air leaks present, your car runs smoothly based upon...

Q: How do you use the push button start system?

Your car is equipped with a push button start/stop system. While this is definitely more convenient than using a conventional key, there are a few things that might take some getting used to. Here’s what you should know about using...