"Check Engine" Light

Most people will recognize one of these warning lights; most cars built since the late 1980's will have one. The common name for this light is the "check engine" light, and automotive professionals will refer to this light as the "malfunction indicator light" or "MIL." Should you see this light rear its ugly head on your vehicle, there is normally no need for panic -- however, you do need to take action soon. Here are the things to look for to help figure out what to do about this light.

First, this light should always come on when you first turn the key from the off to the run position. The run position is that spot in the rotation of the key right before the car actually "cranks over" to start. The light comes on at this time so we can verify the bulb is not burned out. Many of the other warning lights -- such as the oil pressure light, charge indicator (usually looks like a little battery), air bag warning light, and the ABS warning light -- should also come on at this time.

After the engine starts, of course, the light should go off. If the light comes on steady while the engine is running, it means that one or more of the on-board computers has detected a fault. Usually one of the many sensors on the vehicle is giving a reading which indicates a problem in the system, or a sensor value is not logical with normal operation. The problem could be a faulty sensor or an actual fault in the system.

On 1996 or later vehicles, a loose gas cap is a common cause of this light coming on. Check the cap. If it seems loose, or it's gone, tighten it or replace it. Note this will not cause the light to go off right away. It may take several days of driving for the system to recognize the loose or missing gas cap has been corrected. If you cannot wait for the light to go off on its own, bring it in. We will connect our scanner and if a fuel vapor leak fault is indicated, we can turn the light off for you. No charge.

If the problem is not the gas cap, further diagnosis will be needed. Sometimes an accurate diagnosis can be made just using the scanner. In other cases, pinpoint testing with a meter or lab scope will be needed.

If the light goes on, then goes off for a while, a trouble code will be stored in the vehicle's computer memory which we can download with our equipment to get an idea of where the problem is. If you notice the engine running differently when the light is on (lacks power, runs rough, smells or sounds funny) you should get it checked as soon as possible.

If the check engine light is flashing, you do need to take immediate action. The flashing light indicates that severe damage to the engine or emission system may currently be happening. Drive slowly (towing would be better) to the closest repair shop that you trust (hopefully ours) and have it checked.

Many faults that cause the check engine light to come on may be covered by the vehicle manufacturer's warranty even if the basic "bumper to bumper" portion of the warranty has expired. These are usually emission system related components. The components that are covered are clearly explained in your owner's manual. If we diagnose a problem that we think may be covered by the car maker, we will let you know, and in many cases we will call the dealership for you to make that determination.

The "Check Engine" Light On Your Hybrid

If you drive a Hybrid, the "Check Engine" light is just as important as with any other vehicle. One of our customers didn't realize this. You can read what happened on the Hybrid Info page.