Diagnosing Check Engine Lights & Misfires - Tire Review Magazine

Diagnosing Check Engine Lights & Misfires

A flashing check engine light is different from a check engine light that’s lit up and not flashing, and it usually indicates a problem. This content is sponsored by the Automotive Auto Parts Alliance.

Sponsored by Aftermarket Auto Parts Alliance

When it comes to lights popping up on the dash, customers sometimes don’t know what they need or if their vehicle needs immediate attention. This is especially true when it comes to the check engine light. A flashing check engine light is different from a check engine light that’s lit up and not flashing, and it usually indicates a problem.

When the check engine light stays on solid, that means the car is safe to drive. But what if you have a customer who comes into your shop saying they have a flashing check engine light and the ride was pretty bumpy? Well, they probably shouldn’t have been driving at all as a flashing check engine light indicates it’s not safe to drive the vehicle.

The flashing light means harm to other components of the vehicle can occur if the vehicle continues to be driven, and one major component that could be harmed is the catalytic converter.

Diagnosing an Engine Misfire

When a car with a flashing check engine light rolls into your shop, a good place to start the diagnosis process is by using a scan tool to assess what’s going on. Let’s say, for example, the scan brings up a DTC P0301 code. This indicates that cylinder No. 1 is experiencing misfires.

From here, you might check the spark plugs to see if that’s the problem, but the spark plugs look to be in good shape. Since the coils are off, you could replace the cylinder one with cylinder two coil and restart the vehicle. If you find that the misfire is now happening in cylinder No. 2, this means there was a faulty coil over plug. In this scenario, the misfire was fairly easy to figure out, but that’s not always the case. Figuring out the cause of a misfire can sometimes take additional diagnosis.

So, how do you fix this to ensure the vehicle is running smoothly again?

It often depends on the vehicle’s mileage and the condition of the spark plugs. If the spark plugs are in good working condition and the vehicle has lower miles, it’s safe to only replace the cylinder No. 1 coil to get the vehicle up and running again. If the vehicle has high miles and is more than 10 years old, you might recommend to your customer that you replace all of the coil over plugs at the same time.

This article is sponsored by the Aftermarket Auto Parts Alliance.

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