Well actually we have 3 potentiometers. One is under the intake manifold and is a b1tch to change. Have the shop change then ASAP! They can test which ones are failing, most likely it's the pedal or the one buy the oil filter. Get it done because it will get a lot worst. Now that I think about it, an SES light stayed on when I had these problems too.
-2003 M3 Vert
-1967 Mini Cooper