This is a direct replacement thermostat for the N55 engine in the F06/F12/F13 640i and F01/F02 740i/740Li (N55 engine). Your engine's thermostat regulates coolant flow and temperature in the cooling system. When open it allows hot coolant to flow into the radiator to be cooled. When closed the coolant circulates through the engine, where it stays warm. A failed thermostat will either be open or closed with the engine running too cold (poor fuel economy and performance) or too hot (overheating). It can also impact your cabin heating/cooling since that system is drawn from your heater core. On the modern cars like above the car's electronics control the thermostat to regulate various temperature systems in the car.
This is an OEM N55 thermostat manufactured by Behr - the original supplier to BMW for this part, as well as many other cooling components. As the OEM it meets all of BMW's original design, fitment, and performance requirements and is TUV approved. OEM parts are the best alternative to more expensive Original BMW parts because they are virtually identical without the inflated price tag. This part has a two year warranty.
Supersedes BMW Part #11537605431 (11-53-7-605-431)
F12 / F13 (12-18) > 640i
F01 / F02 (2009-2015) > 740Li
F01 / F02 (2009-2015) > 740i