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.

How to read the engine codes without a Nissan CONSULT or scan tool. (Set ECM in Diagnostic Test Mode II)

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).

How to clear the engine codes without a Nissan CONSULT or scan tool.

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.

How to identified the engine codes without a Nissan CONSULT or scan tool.