Self-Diagnostic System: Notes

Prizm LSi uses a Powertrain Control Module (PCM). All other models use a Engine Control Module (ECM). All references to ECM include PCM unless specified otherwise.

The ECM is equipped with a self-diagnostic system, which detects system failures or abnormalities. When a malfunction occurs, ECM will illuminate the CHECK ENGINE light located on instrument cluster. This light is also referred to as the Malfunction Indicator Light (MIL). When malfunction is detected and MIL is turned on, a corresponding trouble code will be stored in ECM memory. To retrieve stored codes, see READING TROUBLE CODES or RETRIEVING CODES (NON-SCAN). Malfunctions are recorded as HARD FAILURES or as INTERMITTENT FAILURES.