Open Loop Mode

This mode is entered when the ECT sensor indicates a high engine temperature that is rising at a dangerously high rate, much faster than expected based on current engine running conditions. This mode can also be entered when all sensors used in fail safe cooling determination have failed.

When this mode is activated, the PCM restricts load and engine speed to below 3000 RPM, starts to slowly lower engine speed to as low as 800 RPM and holds the speed there.

At the same time, the PCM also moves the temperature gauge pointer into the red zone and sets DTC P1285.

If the engine is not switched off after a short period of time, the engine will be totally disabled before major engine damage or seizure occurs, the Powertrain Check Lamp begins to flash, indicating to the driver that the engine will be switched off and sets DTC P1299.

If the driver decides to restart the vehicle, it will be restarted but with DTC P1299 still set and the engine speed is limited to 800 RPM. This mode can only be reset by clearing the DTC using a diagnostic scan tool.