The coolant temperature sensor is necessary for timely notification of engine overheating. Its task is to measure the temperature of the coolant and transfer data to the electronic control unit. Based on the data obtained, the corresponding commands are sent to the units and mechanisms that regulate the ignition timing, crankshaft speed, the amount of fuel in the fuel-air mixture and other important parameters. In some car models, this device is used to switch to an electric ventilation cooling system.

1. AX (ZA-_)
2. BX (XB-_)
3. BX Break (XB-_)
4. C15 Van (VD_)
5. 205 II (20A/C)
6. 205 Mk II (20A/C)
7. 205 I Convertible (741B, 20D)
8. 205 � Convertible (741B, 20D)
9. 205 I (741A/C)
10. 205 � (741A/C)
11. 305 II (581M)
12. 305 Mk II (581M)
13. 305 II Break (581E)
14. 305 Mk II Break (581E)
15. 309 I (10C, 10A)
16. 309 � (10C, 10A)
17. 309 II (3C, 3A)
18. 309 Mk II (3C, 3A)
19. 405 I (15B)
20. 405 I Saloon (15B)
21. See more in applications

The coolant temperature sensor construction

The HELLA brand Sensor, coolant temperature consists of a plastic case with a metal thread, in which there is a thermistor, which is a resistor. The resistance of the resistor decreases as the temperature rises. To provide accurate information, the device must be in direct contact with the coolant.

Some cars are equipped with two sensors, one of which is located at the outlet of the radiator; the second is located at the outlet of the engine. They can be either negative or positive temperature coefficient. In modern cars, the first type of signaling devices is mainly used.