Self-Diagnostic System: Description: Notes

WARNING: This page is about a different car, the 2000 Saturn LW2 and 2000 Saturn LS2. However, it is still accessible from the selected car via links, so may be relevant.

ECM is equipped with a self-diagnostic system which detects system failures or abnormalities. When a malfunction occurs, ECM will store a Diagnostic Trouble Code (DTC) and, in most cases, illuminate the Malfunction Indicator Light (MIL) located on instrument cluster. Malfunctions are recorded as hard failures or intermittent failures.

The following are types of DTC categories:

Type "A"

Emissions related. Illuminates MIL the first time DTC sets.

Type "B"

Emissions related. Illuminates MIL if fault is active for 2 consecutive driving cycles.

Type "C"

Non-emissions related. Does not illuminate MIL, but will illuminate SERVICE light.

Type "D"

Non-emissions related. Does not illuminate any indicator light.