1. Disconnect the wire from the "–" terminal of the battery.
2. Drain the coolant (see "Replacing the coolant").
Helpful tips: You don't have to drain the coolant completely. It's enough to drain the liquid only from the cylinder block. With some skill, you don't have to drain the liquid at all. You need to unscrew the sensor and immediately screw a new one in its place. When quickly replacing the sensor, a small amount of coolant will leak out of the system, which can be easily replenished by adding to the expansion tank.
3. Disconnect the connector with the wire from the coolant temperature gauge sensor.
(The text is copied from the online portal: VAZBOOK.RU)
4. Unscrew the sensor from the cylinder head.
5. Install the coolant temperature gauge sensor in the reverse order of removal.
6. Fill with coolant and check the cooling system for leaks.