Why do we need a coolant temperature sensor?
The coolant temperature sensor is one of the most important details of the electronic system of any car, and it can't be called reliable, no matter in which car and model it is installed. It is this sensor that is responsible for the operation of the forced cooling system of the engine, as well as for the temperature readings on the dash board (if specified by the manufacturer). The start of the engine, mixing of fuel and even fuel consumption depend on its correct operation.
How the temperature sensor works
The coolant temperature sensor is of compact dimensions and is positioned so that to contact directly with the antifreeze in the engine. The data, which this device receives, is transferred in the form of an electrical signal to the engine electronic control unit. The latter, in turn, uses them to prepare the correct fuel mixture and correct the ignition, as well as to control the forced engine cooling system. The data, that are recieved from the sensor, are displayed on the dash board and help the driver to notice the underheating or overheating of the power unit on time.
Drivers remember the existence of a coolant temperature sensor usually only at the time of engine overheating, or when the engine is about to reach a critical temperature. Activation of a "breakdown of engine" indicator or too high (or low) the value of the temperature indicator on the dash board can alert the driver. Often the sensor failure for a long time remains unnoticed. Uncertain start and misfire of the engine, an increase in fuel consumption and a deterioration of the car performance are the indirect signs of a malfunction. In case of a break in the electrical circuit of the coolant temperature sensor or short circuit, the engine cooling fan starts to run at full power and stops turning off. Antifreeze leaks from under the threaded joint of the sensor is also a signal for the need to inspect the device or replace it.
How to check and replace the temperature sensor
It is quite simple to check the operability of the temperature sensor. To do this, you need to arm yourself with a multimeter and test the device for a circuit opening, and also take ohmmeter readings at different temperatures using the parameter list (you can find this information on the Internet). As the temperature of the details increases, the resistance between the sensor leads should reduce. If the device does not respond to a temperature change or if there is a circuit opening, or if the parameters differ from the ones known to be correct, you can safely go to the shop for a new sensor.
It will not be difficult to replace it by yourself. To do this, just cut the electrical connector and unscrew the old sensor, and then replace it with a new one. It is important to remember that the device should be well sealed. Bear in mind that the antifreeze leakage is inevitable when the sensor is unscrewed.