The check engine light on a 2007 Saturn Ion indicates that an irregularity or failure has occurred within the electronic control module (ECM) or computer's sphere of influence. The ECM controls all engine management functions relative to the operation of the engine to exclude the internal components. All computer operations are electromechanical in nature. In order to turn off the check engine light, the indicated fault must be corrected.
Insert the code scanner plug into the OBD II socket, which is located under the dash, on the driver's side just left of the steering column. Turn the ignition key to the run position without starting the engine.
Press the "Read" key on the code scanner. The scanner will withdraw all present codes. The computer has preset parameters and a diagnostic function. The computer recognizes any irregularities in the form of a descriptive code consisting of a letter followed by four numbers. The letter designates the area and the numbers the defective part.
Record the code or codes and cross-reference these with the code sheet. Correct all failures and test-drive the vehicle.
Plug the code scanner into the OBD II port again. Turn the ignition key on, to the run position, with the engine off.
Press the key marked "Erase" to erase the code and reset the computer. This action extinguishes the check engine light until another failure occurs.
