On-Board Diagnostics: Notes

WARNING: This page is about a different car, the 2003 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

Engine Control Module (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, if code is emissions related, illuminate the Malfunction Indicator Light (MIL) located on instrument cluster.

There are 2 paths for accessing on-board diagnostics. It is necessary to access information through both paths, as each path presents some different information.

Generic OBD-II - This provides all generic codes and some OEM codes, serial data required for generic OBD-II and some OEM data, monitor status, pending codes and freeze frame.
OEM - All DTCs, all PIDs, failure records, enhanced scan tool information and all other OEM scanner functions.