SINCE 2004--Professional Auto Diagnostic Factory

How to Know if the Check Engine Light is an Emission Problem

The "check engine" light is perhaps the most confusing of all indicators on your dashboard. It is part of your car's On Board Diagnostic (OBD) system. When it detects a problem in the electronic control system that it cannot fix, the computer turns on a warning light which is usually labeled "check engine."

Look at the other indicator lights on your dashboard to see if any other lights are lit. If you also have an indicator lit telling you that the car has low oil pressure or is overheating you should pull of the road and shut off the engine as soon as it is safe to do so. Have your car checked by a qualified repair shop.

Remove your gas cap and put it back on taking care to ensure that it is tight. If the gas cap is not tightened properly it will cause the "check engine" light to come on. Unfortunately it often takes several trips out with the car before the light shuts itself off so it might take awhile before you know if the problem has been solved.

Check the dipstick in the oil compartment of your engine to make sure it is inserted properly in the tube. If the dipstick is not in tight it may cause the car to idle funny. When the computer senses it the "check engine" light will come on. Again, it might take a little while after tightening the dipstick before the light goes off.

Fill up your gas tank with gas at a different gas station. Sometimes a tank of bad gas can cause a "check engine" light to come on. If your indicator light is caused by bad gas, it will shut itself back off after you run a tank or two of good gas through the car.

Bring the car in to have the code read. Many automotive parts stores and some repair places will hook your car up to a diagnostic reader free of charge. Others charge for the service. The diagnostic reader will give them a code that will help them to determine if it is related to an emission problem.

Tips & Warnings

Do not bring your car in for a state emissions test if the "check engine" light is on. In most states a "check engine" light indicator will cause your car to fail inspection even if the problem has nothing to do with emissions.