Engine Management


Myth-conceptions about the engine check light…

Many people are confused about the check light and why it comes on. We thought we would address some of these common myths about why your check light comes on and clear up some of the fallacies about it.

MYTH 1: The trouble codes will tell you what sensor to replace.

The Check Engine Light directs your attention to a problem. A trouble code description directs you to a circuit or a system. It will not tell you what sensor to replace. It is about as vague as saying that a book is in the automotive section of the library, you know what section to go to , but no clue where to look. This is why there are flow charts or trouble code trees and diagrams to guide you through specific tests to determine what the problem is. Often it is a broken wire, loose connector or some other cause ; other than the sensor itself.


MYTH 2: You can clear the codes by disconnecting the battery.

This can be true of pre-1996 vehicles, and very few, if any, OBD2 vehicles. Some people say ” I disconnected the battery for 15 minutes and the light went out, so it cleared the codes”. Unfortunately it didn’t. It may have reset the ECM and the light is no longer on, but the error code is still there and if the problem has not been repaired, the light will inevitably come back on. The next time you have a problem, now you or the mechanic, who is working on the vehicle is going to have to contend with that code as well as any other code(s) present.

MYTH 3: When the Engine Check Light comes on, it always means you have to replace something.

One of the first things that needs to be done when diagnosing the Check Engine Light is to clear the trouble code(s), road test the vehicle and then recheck the trouble codes. If the codes come back, then start with the lowest number code and go through the flow charts and diagrams.

MYTH 4: The Check Engine Light means an O2 sensor problem.

Anyone who has taken this to be true and has spent quite a bit of money on replacing oxygen sensors knows this not to be true. Firstly, you nor anyone else, will be able to determine the problem until you have determined the trouble codes. Even if it is the oxygen sensor code, most of the time there are other reasons for the code to be displayed, other than the O2 sensor itself.

We hope this clears up some of the misconceptions people may have re the Check Engine Light. So if you are having problems with the Check Engine Light coming on, please do not hesitate to contact us to arrange an appointment and we will use the latest scanning equipment currently available to determine the problem.