This O-ring for the 'Straight type' Temperature Sensor fits the Thermostat Housing p/n G2NME1125.
Fits the following models:
2007-02/2013 R56 MINI Cooper and Cooper S Hatchback
2008-02/2013 R55 MINI Cooper and Cooper S Clubman
2009-02/2013 R57 MINI Cooper and Cooper S Convertible
2012-02/2013 R58 MINI Cooper and Cooper S Coupe
2012-02/2013 R59 MINI Cooper and Cooper S Roadster
2011-02/2013 R60 MINI Cooper and Cooper S Countryman
There are two different types of coolant temperature sensors, a 'straight' type and an 'angled' type. Make a physical inspection of the thermostat housing on your MINI to see which one your MINI requires.
Some models manufactured between 08/2010-03/2012 have the temp sensor 'molded into' the thermostat housing and are not replaceable. If you have one of these housings with the molded in temperature sensor and you don't have any coolant leaking issues around the housing, there is a Temperature Sensor Bypass Adapter to work around the faulty coolant temperature reading. If you have coolant leaking issues, you should update to a newer version of the thermostat housing - take a look at the Thermostat Housing Application Guide to see which one you need.
For a listing of all engine Cooling System replacement parts, see Mini Cooper Engine Cooling System Repair Parts.