Thermostat Monitoring

Description





The diagnostic checks for a partially open thermostat, under conditions when the thermostat would be expected to be shut.

A second coolant temperature sensor is installed in the outlet from the radiator. If the enablement criteria are met and the engine coolant temperature is less than the normal thermostat opening temperature, then a fault will be detected if the radiator outlet temperature has increased by more than a threshold.

Additionally, if a start temperature dependent timer has expired without the thermostat opening temperature being achieved, then a fault will also be detected. This timer is suspended if the vehicle is operated in over run fuel cut off and it will be extended if the vehicle is operated at idle, since both these conditions slow down the rate of engine warm up.

Monitoring Structure











Drive Cycle Information
P0128 Drive Cycle D
P2184 Drive Cycle D
P2185 Drive Cycle D
P2183 Drive Cycle D