Symptoms of a Bad or Failing Ignition Coil

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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)[https://www.yourmechanic.com/services/check-engine-light-is-on-inspection] 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.


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Chris

15 years of experience
419 reviews
Chris
15 years of experience
Honda Accord - Starter - San Francisco, California
I needed a Starter replaced, the accessibility on it was so limited. Chris had serviced another vehicle of mine previously, I was so impressed then with his knowledge and abilities, thus requested for him specifically. Again, just as the previous time, contacted me and arrived promptly. He worked on it immediately and got my back my car back in business within the promised time frame. I have dealt with many car technicians in the past, seriously, no one comes close.
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great service.

David

15 years of experience
611 reviews
David
15 years of experience
Mercedes-Benz E550 - Brakes, Steering and Suspension Inspection - Crockett, California
very knowledgeable and courteous but can improve on timeliness.

Peter

42 years of experience
1301 reviews
Peter
42 years of experience
BMW 325 - Tail Light Lens Replacement (Driver Side) - Glendale, Arizona
nothing else to say /cheque below

Duane

24 years of experience
395 reviews
Duane
24 years of experience
Chevrolet Silverado 1500 - Starter - Santee, California
Duane is the man,he showed up on time did the job in efficient manner.very professional explained exactly what he did from testing to fixing the problem. Thanks again Donald

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