Fail-Safe Cooling Strategy

The fail-safe cooling strategy is activated by the PCM only in the event that an overheating condition has been rectified. This strategy provides engine temperature control when the cylinder head temperature exceeds certain limits. The cylinder head temperature is measured by the cylinder head temperature (CHT) sensor.

A cooling system failure such as low coolant or coolant loss could cause an overheating condition. As a result, damage to major engine components may occur. Along with a CHT sensor, the fail-safe cooling strategy is used to prevent damage by allowing air-cooling of the engine. This strategy allows the vehicle to be driven safely for a short period of time when an overheat condition exists.

The engine temperature is controlled by varying and alternating the number of disabled fuel injectors. This allows all cylinders to cool. When the fuel injectors are disabled, their respective cylinders work as air pumps, and this air is used to cool the cylinders.