Envoy, Rainer, Trailblazer 2006-2007



The Engine Coolant Temperature (ECT) sensor is used to monitor the temperature of the engine coolant. Its resistance changes in proportion to coolant temperature. Input from the coolant sensor tells the computer when the engine is warm so the PCM (4.2L) or ECM (5.3L and 6.0L) can go into closed loop feedback fuel control and handle other emission functions (EGR, canister purge, etc.) that may be temperature dependent.