Check Engine Light On?
What does that light mean anyway?
Web2Carz Contributing Writer
Published: July 11th, 2011
The infamous light reads “Check Engine Soon” and you have found yourself in a predicament. If you are like millions of other drivers, you may just ignore it. If you have a quarter million miles on that old hand me down, you might just cover the annoying light with electrical tape, and drive along as if nothing has happened—not recommended. Perhaps, none of these options are plausible, and your illuminated check engine light is actually a worry.
Check Engine lights can come on for many reasons. It could be something serious such as engine misfires, or even a simple issue such as a loose gas cap. Before you lose your cool, be happy to know that your vehicles On Board Diagnostic system (OBD) is actually working as it was designed to. So relax, do not pull off to the shoulder if your check engine light comes on unless your vehicle is unsafe to drive. Remember, the Check Engine Light comes on not to inform you of dire destruction, but as an indicator that a service is needed.
How the Check Engine Light Works
Most vehicles on the road today are equipped with dozens of sensors that send information to your onboard computer, or ECU. Within your ECM is an On Board Diagnostic system, or OBD, which translates sensor irregularities into specific codes that identify system abnormalities and possible malfunctions.
Codes stored in your vehicles ECU can be single sensor irregularities, or consist of multiple abnormalities. Designed as a diagnostic resource for technicians, these OBD codes can be read with handheld scanners so the problems can be more easily determined. Remember, an illuminated check engine light does not mean your car is going to break down.
What to do if your Check Engine light is on?
Do not just put it aside for months, but make plans for visiting a service center as soon as possible. If you are not experiencing notable engine or driving irregularities, you can actually pull the codes yourself. Before you get brazen, here are the steps precautious drivers and smart consumers will take when determining why a check engine light is on.
1. Check other Gauges
If your check engine light illuminates, the first thing you should do is check other dashboard gauges. Is your oil pressure and coolant temperature out of the norm? If so, you should find a way to safely pull over and make plans to visit a service center.
2. Vehicle Under Warranty? Bring it in.
If you have a newer car with a check engine light on, feel distraught. If you take care of your vehicle regularly, there is no reason a check engine light should come on if the car is still under warranty. If a warranty still applies to the car, do not be a mechanic. Take the car into your service center right away, and get your moneys worth.
3. Determine if Car is Behaving Abnormally
Is the vehicle driving unusually? Are there unusual sounds? Is the vehicle shifting, accelerating and breaking correctly? If the vehicle does behave unusual following a check engine light coming on, find a way to safely stop driving and make plans to bring it into service. Taking care of the problem as soon as possible will prevent even more expensive damage from taking place.
4. Check the codes yourself.
Your neighborhood Auto parts stores have On board diagnostic (OBD) scanners. These code-reading devices attach, in most vehicles, into a port located under the drivers-side dashboard. In most cases, you can actually go inside the parts store and ask a sales representative to come out and read the codes for you. They will attach the scanner, read the codes, and actually print you a summary. This summary will include codes and possible causes of the check engine light.
5. GM Vehicle? Call Onstar if Applicable.
GM Vehicles made after 1998 may be equipped with Onstar. If you have a subscription, you can call them and they will actually be able to access your ECU remotely to determine what may be causing the check engine light to come on. In addition, they can also suggest future actions and may even be able to arrange a service appointment at your local dealer center.
6. If towing or hauling heavy loads
Consider being even more vigilant in determining if driving problems are apparent, and make plans as soon as possible for service. A vehicle that is towing or hauling heavy loads may suffer increased damage if check engine light is ignored.
7. Tighten your Gas Cap
In some instances, the check engine light may be on because the gas cap is not closed all the way, or has malfunctioned. Be sure to check the status of the cap, and have it replaced if it is broken.


