Engine Coolant Temperature (ECT).
is a critical engine management component that monitors the internal temperature of your vehicle's engine by measuring the heat of the coolant. It functions as a "thermometer" for the Engine Control Module (ECM), providing data used to adjust vital functions such as fuel injection, ignition timing, and cooling fan operation. (P0115-P0119)
A broken Engine Coolant Temperature (ECT) sensor causes the engine control unit to receive incorrect data, leading to a check engine light, poor fuel economy, rough idle, stalling, and potential overheating. It commonly causes the car to stay in "open-loop" mode, running too rich, or fails to activate cooling fans.