On Board Diagnostic (OBD) System: Introduction

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 including:

Fig 1: On Board Diagnostic (OBD) Chart

Courtesy of NISSAN MOTOR CO., U.S.A.

The above information can be checked using procedures listed in the table below.

Fig 2: Identifying Procedures List Table

Courtesy of NISSAN MOTOR CO., U.S.A.

1. 1st trip DTCs for self-diagnoses concerning SRT items cannot be shown on the GST display.
2. When DTC and 1st trip DTC simultaneously appear on the display, they cannot be clearly distinguished from each other.

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. (Refer to FAIL-SAFE CHART  .)