The ECM has an on board diagnostic system, which detects malfunctions related to engine sensors or actuators.
The ECM also records various emission-related diagnostic information
The malfunction indicator lamp (MIL) on the instrument panel lights up when the same malfunction is detected in two consecutive trips (Two trip detection logic), or when the ECM enters fail-safe mode.

1. Confirm that accelerator pedal is fully released, turn ignition switch ON and wait 3 seconds.

2. Repeat the following procedure quickly five times within 5 seconds.

   1. Fully depress the accelerator pedal.

   2. Fully release the accelerator pedal.

3. Wait 7 seconds, fully depress the accelerator pedal and keep it for approx. 10 seconds until the MIL starts blinking.

4. Fully release the accelerator pedal.

5. ECM has entered to Diagnostic Test Mode II (Self-diagnostic results).

1. Set ECM in Diagnostic Test Mode II (Self-diagnostic results).

2. Fully depress the accelerator pedal and keep it for more than 10 seconds. The emission-related diagnostic information has been erased from the backup memory in the ECM.

3. Fully release the accelerator pedal, and confirm the DTC 0000 is displayed.

A particular trouble code can be identified by the number of four-digit numeral flashes. The ?zero? is indicated by the number of ten flashes. The length of time the 1,000th-digit numeral flashes on and off is 1.2 seconds consisting of an ON (0.6-second) - OFF (0.6-second) cycle. The 100th-digit numeral and lower digit numerals consist of a 0.3-second ON and 0.3-second OFF cycle. A change from one digit numeral to another occurs at an interval of 1.0-second OFF. In other words, the later numeral appears on the display 1.3 seconds after the former numeral has disappeared. A change from one trouble code to another occurs at an interval of 1.8-second OFF. In this way, all the detected malfunctions are classified by their DTC numbers. The DTC 0000 refers to no malfunction.

*The Following is not an standard list, some code may vary for different models. Please see the "Engine Control" section of the service manual for more information.