Radiator Fan Switch 91/99C, BMW - E30, E36, E34, E24, E32, E31, Z3

This part is listed by BMW as BMW part number 61311378073 (61-31-1-378-073) and is described as the Radiator Fan Switch used on most E30, E36, E28 M5, E34, E24 M6, E32, E31, and Z3. This sensor is typically found on the side of the radiator or near the outlet of the radiator. It measures coolant temp and is used to turn on the auxiliary fan to help control engine temps at low speeds. It's a two-speed switch - 91C for low speed and 99C for high speed. A failing switch will cause one or both fan speeds to fail.

This part is also used to convert the 1987 cooling system to the late 1988 E30 cooling system, which also requires the radiator, expansion tank, and additional hoses.

A crush sealing washer is not included and should be ordered separately - see Related Items below.

This is a Genuine BMW fan switch with a two year warranty. Buying a Genuine part will usually be more expensive than an OEM or aftermarket brand but you are assured that it meets BMW's designs for fitment, performance, and longevity. It will also be the very latest design, incorporating any updates or revisions that an aftermarket brand typically will ignore.

For full BMW fitment information or for assistance from one of our BMW experts, we recommend calling us 877-639-9648.