coolant temperature sensor

The coolant temperature sensor checks how hot the engine’s coolant is running. The coolant temp sensor is usually located on the intake manifold or the water inlet to the engine. This is usually close to or in the thermostat housing, which is at the end of the hose coming from the radiator. The sensor tells the ecu if the engine is cold and has not been warmed up. This activated the enrichening maps in the computer. It is essentially a “choke” for the engine. When engines are cold they need more fuel to run properly until they’ve heated up to a certain temp. Usually the normal fuel maps will be used when the engine reaches within 20 or 30 degrees below where the thermostat opens. That is why it’s important to not lower the thermostat temp or it could keep the engine running rich all the time, wasting fuel. If you have a problem with your coolant sensor you can test it. This test also works for a MAT (manifold air temp) sensor. First check the plug to make sure the wires look good and the plug is tight. Run the car for five minutes. Shut off the car and remove the sensors plug. You will need a volt/ohm meter to check the ohms. Set the ohm meter on 20k ohms. There are three types of temperature plugs. With a single wire sensor, touch the one wire and use the other wire to touch the brass or metal on the sensor. Two wire sensor, just touch the two wires. Three wire temp sensor, touch the center and one of the outers. The ohm value should be higher than 500 ohms or it is not good and needs to be replaced.