Check Engine Lights - What to do ?

A Check Engine Light(CEL) is a yellow warning engine symbol or the words "CHECK ENGINE" that appears on the dash board, during driving or even while starting the car. First thing is do not panic.The major events - like low oil, temperature or battery have their own separate warning lights, so do not panic. A CEL could mean a simple thing like a loose gas cap to a serious issue like a failed or damaged spark plug.

The CEL is part of the cars onboard diagnostics (OBD) system. Since the 1980s, computers increasingly have controlled and monitored vehicle performance, regulating such variables as engine speed (RPM), fuel mixture, and ignition timing. In some cars, the computer also tells the automatic transmission when to shift. When it finds a problem in the electronic-control system that it can't correct, the computer turns on the yellow CEL. The computer also stores an error code in its memory that identifies the source of the problem, such as a malfunctioning sensor or a misfire. This code can be read with your OBD readers.When the OBD II format came out in 1996,carmakers were required to install a much more complicated system that essentially acts like a built-in emissions check system. The computer monitors and adjusts dozens of components and processes. For example, it continually samples exhaust emissions as they come out of the engine and again when they leave the catalytic converter, a device that removes carbon monoxide and hydrocarbon pollutants from the exhaust. The system also monitors your car's fuel system to ensure that gasoline vapors are not escaping into the atmosphere through a leak or even a loose or missing gas cap. In most cases, if a problem occurs, the computer will wait to see if it corrects itself before turning on the light.  


If you get a check engine light, you should be able to read the diagnostic codes using your OBD reader. These codes are also called Diagnostic Trouble Codes (DTCs) and are 4 or 5 digits and usually start with the letters P. Write down the DTCs your tool reads, on paper. Do consult your cars manual on any information on the Diagnostic codes If you don't have an ODB reader and you have  popular make car, some discount parts stores can read it for you for free. You should be familar with the location of the OBD port on your car. Once you have the diagnostic codes , using your favorite search engine you should be able to quickly find out what the underlying problem is.

Here are some examples :

    1.) Misfire codes :- Ignition or bad spark plugs

    2.) Emission - Thermostat bad

    3.) O2 Sensor - Bad Voltage - Will need new O2 Sensor   

Now is also a good time to RESET the CEL using your ODB tool. The purpose of doing it is to remove any one time false flags. By a reset you let the computer verify the issue and if the problem persists , it can turn on the CEL one more time. If it indeed is a issue the  CEL can come on with in a few seconds,minutes,hours or days of the RESET. So if the CEL repeats, and the error codes match it will indeed confirm the issue. If you approach a dealer or repair shop to fix the issue, you will be the perfect turkey for them to "fix" many many things "wrong" with your car.  So don't do that , instead read the code and find out what it is. If is an O2 sensor , it may be cost you $80 for a BOSCH O2 Sensor. If you don't want to deal with putting it on your exhaust your local muffler guy will be happy to put it in for less that $30. I do know of a guy who took his check engine light in to repair shop and ended up spending $650 to replace an O2 sensor. So there it is folks , on how you can save!!!