Coolant Temperature Sensor

This is the coolant temperature sensor used in many BMW models from the mid-1990s to the mid-2000s. The engine computer relies on the coolant temp to set the fuel mapping for the engine. As the car warms up the computer changes the fuel mixture. If your car is running a bit rich (too much fuel) it could be because this sensor is failing and not sending the correct info to the computer.

This sensor is located in a variety of places depending on the engine. But it's one of those easy replacement items 'while you're in there' when doing a water pump or thermostat replacement.

This coolant temp sensor fits the following BMWs:
1996-1999 E36 BMW 323is 323ic 328i 328is 328ic M3, located in cylinder head
1999-2003 E39 BMW 540i, located on side of water pump
1999-2001 E38 BMW 740i 740il, located on side of water pump
1995-1996 E38 BMW 750il, located on side of water pump
1990-1999 E31 BMW 850i 850ci, located on side of water pump
2000-2006 E53 BMW X5 3.0i, located in cylinder head
2000-2006 E53 BMW X5 4.4i/4.6is/4.8is, located on side of water pump
1997-2002 Z3 BMW Z3 2.5i Z3 3.0i, located in cylinder head