On-Board Diagnosis System - Subaru LEGACY 2002 Quick Reference Index

6. On-board Diagnosis System

A: GENERAL
! The on-board diagnosis system detects and indicates a fault by generating a code correspond-
ing to each fault location. The malfunction indicator lamp (CHECK ENGINE light) on the combina-
tion meter indicates occurrence of a fault or abnormality.
! When the malfunction indicator lamp comes on as a result of detection of a fault by the ECM,
the corresponding diagnostic trouble code (DTC) and freeze frame engine condition are stored in
the ECM.
! The Subaru Select Monitor (SSM) can read and erase DTCs. It can also read freeze frame data
in addition to other pieces of engine data.
! If there is a failure involving sensors which may affect drive control of the vehicle, the fail-safe
function ensures minimum level of driveability.
B: FAIL-SAFE FUNCTION
For a sensor or switch which has been judged faulty in the on-board diagnosis, the ECM, if appro-
priate, generates an associated pseudo signal to keep the vehicle operational. (The control be-
comes degraded.)
ON-BOARD DIAGNOSIS SYSTEM
FU-33
Fuel Injection (Fuel System)