Fail-Safe Function
WARNING: This page is about a different car, the 2003 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.
When a malfunction occurs within the engine control system, the PCM maintains control over the fuel injection system, idle speed control system, etc. PCM controls these systems by using calculated values and/or backup programs stored within the PCM. This function is called the fail-safe function. With the fail-safe function, a certain level of engine performance is available even when a malfunction occurs. The fail-safe function prevents a complete loss of engine performance. The systems covered by the fail-safe function are:
- Mass Air Flow (MAF) sensor.
- Intake Air Temperature (IAT) sensor.
- Throttle Position (TP) sensor.
- HO2S heater circuits.
- Knock Sensor (KS) system.
- Central Processor Unit (CPU) in the PCM.
- Fuel cut-off for ignition system failures.