The design and work of system of onboard diagnostics is in essence borrowed from the modern MPV (LW) model with the GY/FS engine, except for the conditions given below.

Diagnostic codes, controlled parameters and parameters of modeling are changed according to rules.

KOEO/KOER self-checking function is introduced. Therefore the existing malfunction or successful repair are confirmed at once.

Process of storage of incomplete codes is changed as follows.

On the modern MPV (LW) model with the GY/FS engine incomplete codes are inaccessible. In the Mazda 3 model (GG), however, the incomplete code is remembered in the PCM block during a riding cycle.

On the modern MPV (LW) model with the GY/FS engine incomplete codes are erased at record of diagnostic codes. In the Mazda 3 model (GG) even if the diagnostic code remains, the PCM block does not erase an incomplete code before emergence of the normal state (malfunction is eliminated).

The operating mode of a control lamp of MIL of a riding cycle 2 types is changed as follows:

The PCM block decides that in the first riding cycle there is a malfunction when the diagnostic code which was written down in the PCM block during the previous riding cycles is found.

The PCM block decides that malfunction is available in the second riding cycle.