"Check Engine" light warning

(This service can be performed by a novice on most vehicles)

If you see a "check engine" or a "service engine soon" light in your instrument cluster; your car has stored a diagnostic trouble code. This means the computer system on your vehicle has detected a problem with the various systems it controls. Your car or truck has many different sensors that monitor the various vehicle systems. If the trouble code light has been illuminated your vehicle enters into "limp mode" this means it is running without the computers full assistance and is on a predetermined program that can cause poor mileage and increased emissions. An engine trouble coder reader is an easy to use. All 1996 vehicles and newer utilize a "D" style plug in connector that connects to the code reader. Most vehicles connector is located at the drivers compartment. Once the code reader is plugged in you can retrieve trouble codes the engine computer has stored has in its memory. These codes are the same codes the dealer and repair shops use to replace sensors and clear codes.

1. Malfunction Indicator Lamp

The MIL has illuminated during driving this means there is a malfunction trouble code stored in the vehicles computer.

2. Locate Your Vehicles Computer Connector (ALDL - assembly line data link.)

Locate your vehicles computer connector (ALDL) most vehicles are on the drivers side lower. Some vehicles you might need to look around a little, on the passengers side, and around the center console under a plastic cover.

Connecting to the code scanner to read codes

Connect your code reader to the under dash connector. The code reader will automatically turn on and prompt you to the next step for code retrieval. Once the code has been identified look up the identification code on the trouble code chart supplied with your code reader. After repair has been made clear trouble codes and recheck system. After codes have been cleared the computer system is ready for internal testing, this means that while the car or truck is operation the onboard computer is performing tests. These test are called "monitors" most cars have between 4 and 8 monitoring systems. The computer performs tests for about 30 to 60 miles before it fully resets.

Common problems

1.  After a car repair has been performed the MIL indicator will illuminate because the technician neglected to plug in a sensor.

2. A blown fuse can cause the MIL to illuminate.

3. A shorted sensor can cause the MIL to illuminate.
 

Also see:

How to check - service engine soon light or check engine light
How to check engine miss
How gas engines work
How hybrid engines work
How to check for low power
How to check for over heating
How to replace spark plugs