What You Don't Know About Your Check Engine Light.

When the check engine lamp lights on your dash, do you know what it means? I don't. Your computer stores fault codes for a variety of reasons, most of them related to emissions sensors. The computer is constantly redefining how much fuel to feed the engine, and when to deliver spark. It does this based on data programmed to it by the vehicle manufacturer, and uses many sensors in the engine bay and exhaust to update it on the conditions the engine is experiencing. Under these conditions, it will modify the fuel rate and ignition advance as required, to a point. If the check engine lamp is lit, the computer has determined that the feedback from a sensor is not in line with what it has been programmed to expect. This can result in poor performance and fuel economy. What needs to be done? Someone has to "pull codes," by hooking up a special computer to the car that can interpret the codes. This is only part of the process. I have met many people who think that because the computer registers an irregular signal from an oxygen sensor that the sensor must be replaced. It is entirely possible that the irregular signal may be presented because of other issues. Perhaps there is an exhaust leak upstream of the sensor, or the engine is not operating as expected. This must be physically diagnosed. So, scan for codes, have diagnosed by someone educated in automotive operations. As a side note, if your check engine lamp is flashing, stop driving the car. A flashing check engine lamp indicates a significant misfire, and the unburnt fuel from the misfiring cylinder(s) can go straight to your catalytic converter(s) and cause premature failure. The repair costs may become overwhelming, so it is recommended to have towed to a trusted service center for a proper diagnosis.