ON-BOARD DIAGNOSTICS (OBD) - NORTH AMERICAN SPECIFICATION (NAS) VEHICLES ONLY
The ECM monitors performance of the engine for misfires, catalyst efficiency, exhaust leaks and evaporative control loss. If a fault occurs, the ECM stores the relevant fault code and warns the driver of component failure by illuminating the Malfunction Indicator Light in the instrument pack.
On vehicles fitted with automatic gearbox, the ECM combines with the Electronic Automatic Transmission (EAT) ECU to provide the OBD strategy.