Thermoswitch at the radiator outlet
Examination
1. Have the sensor checked by a BMW dealer.
Withdrawal
2. The thermal switch is located in the bottom branch pipe of a radiator. Before removing the thermal switch, the engine and radiator must be cool.
3. Disconnect the negative cable from the battery.
4. Either partially drain the coolant to a level below the thermal switch, or prepare a plug that can be used to plug the hole while the thermal switch is not available. If you prefer a cork, then be careful not to damage the radiator, and do not bring any dirt into the radiator with the cork.
5. Disconnect the electrical wiring from the thermal switch (pic. 7.5).
6. Release the temperature switch from the clamp and remove it from the radiator. Remove the sealing ring from it.
Installation
7. Install the sensor in reverse order. Replace sealing ring. Finally, fill the cooling system with liquid.
8. Start the engine and warm it up to operating temperature. Wait for the fan to turn on and make sure that the cooling system is maintained at the desired temperature.
Coolant temperature sensor
Examination
9. Have the sensor checked by a BMW dealer.
Removal - N42 engine
10. Either partially drain the coolant to a level below the sensor, or prepare a plug that can be used to plug the hole during its absence. If you prefer a cork, then be careful not to damage the hole for the sensor, and do not bring any dirt with the cork.
11. The sensor is located on the left side of the cylinder block under the intake manifold (pic. 7.11). To access the sensor, remove the alternator (see 5A).
12. Disconnect the electrical connector from the sensor and unscrew the sensor from the cylinder block. Remove the sealing ring.
Removal - M43TU engine and 6-cylinder engines
13. Either partially drain the coolant to a level below the sensor, or prepare a plug that can be used to plug the hole during its absence. If you prefer a plug, then be careful not to damage the hole for the sensor and do not bring any dirt into the cooling system with the plug.
14. The sensor is screwed on the left side into the cylinder head, under the intake manifold.
15. Disconnect from the gauge electroconducting. Unscrew the sensor from the cylinder head and remove the sealing washer (pic. 7.15).
Installation
16. Put a new sealing washer on the sensor, screw the sensor into the cylinder head and tighten it securely.
17. Connect the electrical wiring to the sensor. Fill the cooling system.