Description

Thermostat Monitoring Description





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

A second ECT sensor is installed in the outlet from the radiator. If the enablement criteria are met and the ECT is less than the normal thermostat opening temperature the diagnostic will run.

The diagnostic compares the difference between ECT and the radiator outlet temperature. This gives the temperature drop across the radiator.

If the temperature drop is less than a threshold, and there is flow across the radiator, this is caused by leakage through the thermostat.