1. Prepare the vehicle for the operation (see "Preparing a car for maintenance and repair").
2. Release the wiring harness connector retainer and disconnect it from the coolant temperature sensor.
3. Connect the negative probe of the voltmeter to the engine ground.
4. Turn on the ignition and measure the voltage at terminal "A" of the wiring harness connector with a voltmeter. The voltage at the terminal should be at least 12 V. If the voltage does not reach the connector, this indicates a fault in the power supply circuit or the ECU.
5. Turn off the ignition.
6. Key by 19 mm we unscrew the temperature sensor and remove it together with the sealing washer from the housing of the engine cooling system pipe.
7. Connect the ohmmeter to the sensor terminals.
8. Fill the container with hot water and immerse the working part of the sensor in it. Record the readings of the device at a temperature of about 90°C. As the water cools, measure the resistance of the sensor at a temperature of 80, 60, 40, 30 and 20°C.
The resistance of a working sensor should approximately correspond to the data specified in the table:
| Coolant temperature,°C | Coolant temperature sensor resistance, Ohm |
| 90 | 250 |
| 80 | 340 |
| 60 | 670 |
| 40 | 1500 |
| 30 | 2250 |
| 20 | 3500 |
(The text is taken from the online resource VazBook.ru)
If there are large discrepancies in the data, we replace the sensor.
Installation
1. The sensor is installed in the reverse order.
2. Start the engine and make sure there is no coolant leak from under the sensor. If necessary, tighten it additionally. If this method does not eliminate the leak, reinstall the sensor, applying heat-resistant sealant to its threaded part.