A 2001 Chevy Blazer is equipped with an on-board diagnostic computer system (OBD II) that monitors the performance of the emissions and other systems on your Blazer. This computer keeps track of the routine servicing needs of your vehicle and sends you an alert on the instrument panel that reads "Service Engine Soon." Connecting a diagnostic code scanner to the vehicle allows you to read the trouble codes so you know what servicing your vehicle needs. Once you have the servicing performed, you can erase the trouble code yourself, thus resetting and turning off the "Service Engine Soon" light.
Find the OBD II port under the dashboard on the driver's side of the car. It is between the steering column and the driver's door.
Plug the diagnostic code scanner into the OBD II port. Put the key into the ignition and turn it to the "On" position, but don't start the engine. This powers on the diagnostic code scanner.
Wait for the trouble codes to appear on the scanner. Write down these codes on a piece of paper.
Turn off the vehicle and remove the scanner. Look up these codes in a service manual, or take them to your mechanic and have the servicing performed.
Repeat steps 1 and 2. Wait for the trouble codes to appear. Press "Delete" or "Clear Trouble Codes." This clears the codes from the OBD II computer's memory and resets the light.
Remove the scanner from the port. Turn off the vehicle. Wait one minute. Turn the engine on and verify that the "Service Engine Soon" light has been turned off on the instrument panel.