MINI OEM Map Sensors for all Gen 1 cars.
Sensor 648 fits the R50 MINI Cooper 2002-2006, as well as the R53 MINI Cooper S 2002-2006, the R52 MINI Cooper 2004-2008, and the R52 MINI Cooper S 2004-2008. This sensor reads how much air pressure is being brought into the car post throttle body. It is located in the intake manifold in the MINI Cooper and is located next to the valve cover on the MINI Cooper S (see photos).
Sensor 679 is for the R53 MINI Cooper S 2002-2006 and the R52 MINI Cooper S 2004-2008. This sensor reads how much boost the car is making from the supercharger, as well as takes a temperature reading. Sensor 679 is the T-MAP sensor and is located on the front manifold of the MCS (see photos). It is also referred to as downstream in many of the P-Codes, even though it is post Supercharger, which makes the MAP sensor upstream. This rule is only good for the MINI Cooper S.
Read the codes so you can replace the correct part, the first time. Without reading the codes and doing the correct diagnosis, you're just throwing parts at the car, and that can get costly. Here at the shop, we see sensors go from time to time, but there is no rule of thumb to say sensor X always fails, and you don’t have to replace both when doing this repair. However, if you are doing a motor build, it is recommended.