Q: Three coils are misfiring. Do I have to change all three at the same time? Can I change the spark plugs first?

asked by on

I am looking for the most cost efficient way to take care of this.

My car has 124000 miles.
My car has an automatic transmission.

Ignition coils deliver the spark to the spark plugs. If you are confident that the coils are in fact misfiring, changing the spark plugs will not fix your problem. Ignition coils are coated with a varnish-like insulation that becomes brittle over time after being stretched then contracted repeatedly The insulation develops small fractures that open when heated and close when cooled. When open, they allow shorting of coil windings and decrease or eliminate the coil’s ability to function. This type of temperature cycling happens because every time you shut the engine off, the fan stops running, the coolant stops flowing and the temperature under the hood rises. Every time you start the engine again the coolant flows, the fans turn on, and the temperature drops. When this heat dissipates and is absorbed under the hood, it is trapped causing this cycling effect. I would recommend having an expert from YourMechanic come to your location to take a look at your vehicle to properly diagnose your ignition system.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Three coils are misfiring. Do I have to change all three at the same time? Can I change the spark plugs first?

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: my coolant becomes empty after two days of filling it up

You have a leak. The only question is where. YourMechanic will pressurize the cooling system when COLD which should reveal the leak without too much trouble. A common leak would be through the water pump bearing weep hole, especially if...

Q: Q: Average 10.5 mpg

It is best to abide by the recommendations stated in the owners manual. Turning off traction control may allow more stress to be put on the vehicle and cause accelerated wear in some areas. The traction control is not directly...

Q: Check Engine codes. Need warranty for mechanic service work, any examples to ask for?

Hello there, thank you for asking about your 2001 Saab 9-3. These codes can come up if the engine needs a tune up, if it has bad coils, or even if you have dirty fuel injectors. Due to the age...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...