Cooling System: Description and Operation: Overview

Engine Cooling

Overview

Fail Safe Cooling

For vehicles equipped with a 2.0L GTDI (Gasoline Turbocharged Direct Injection) engine, a strategy is built into the PCM (Powertrain Control Module) that will control the engine if it starts to overheat.

Stage 1 of the strategy commences if the engine starts to overheat. The CHT (Cylinder Head Temperature) sensor transmits a signal to the PCM (Powertrain Control Module), which moves the temperature gauge pointer into the red zone.

If the engine is not switched off and the temperature continues to rise, the Powertrain Check Lamp is illuminated. This indicates to the driver that the engine is approaching critical limits and should be stopped. At this point DTC (Diagnostic Trouble Code) P1285 is set in the PCM (Powertrain Control Module) which can be retrieved using a scan tool.

Stage 2 of the strategy commences if the lamp and temperature gauge are ignored by the driver. The PCM (Powertrain Control Module) will start to control the engine by cutting out 2 cylinders and restricting the RPM (Revolutions Per Minute) to below 3,000 RPM (Revolutions Per Minute). Simultaneously the MIL (Malfunction Indicator Lamp) illuminates. This indicates that long term engine damage can occur and vehicle emissions will be affected. At this point DTC (Diagnostic Trouble Code) P1299 is set in the PCM (Powertrain Control Module) which can be retrieved using a scan tool.

Air is then drawn into the deactivated cylinders. This helps to control the temperature of the engine internal components. The deactivated cylinders are alternated to allow even cooling of all the cylinders.

NOTE: If the driver is using a high percentage of throttle travel (for example, an overtaking maneuver) when the PCM (Powertrain Control Module) starts engine deactivation (Stage 2), the deactivation will be delayed for 10 seconds.

NOTE: After 2-cylinder operation has begun, the engine will not revert to 4-cylinder operation, even if the temperature should fall, until the ignition is switched off and then on again.

NOTE: The MIL (Malfunction Indicator Lamp) can only be extinguished by using a scan tool after the fault has been rectified and the DTC (Diagnostic Trouble Code) cleared.

Stage 3 of the strategy will commence if the engine temperature continues to rise. This results in the engine being totally disabled before major engine damage or seizure occurs. The Powertrain Check Lamp will begin to flash, indicating to the driver that the engine will be switched off after 30 seconds. This allows the driver time to choose a suitable parking place.