Where is the coolant temperature sensor installed in a car?

[LeilaniLynn]

The coolant temperature sensor is installed at the position in front of the cylinder head thermostat at the interface between the engine and the transmission. Its working principle is: The engine ECU receives the signal from the coolant temperature sensor as a correction signal for engine fuel injection and ignition, while also using it to control the coolant, fan, and air conditioning. Symptoms of a faulty coolant temperature sensor include: 1. Difficulty starting the engine when cold, unstable idle operation, or insufficient power during acceleration; 2. Under normal engine starting, idle operation, and acceleration conditions when hot, the engine fault indicator light remains on.