Brake switch cause limp mode?

[Burnzybubbles]

So I picked this A8 up yesterday, it drove back and for some fortunate reason it didn’t hit limp mode for about 90 Miles, kickdown worked if a little lathargic, lock up was fine and didn’t seem to slip at all.

Now the fault codes are the g195 implausible signal 17105 and brake switch electrical malfunction 17087 these codes where cleared and return by the way.

The reason I wondered if it’s the brake switch as if I cycle ignition and drive straight off the box stays out of limp mode, but if I hold the brake pedal for any amount of time at standstill the box usually clunks into limp mode, I can brake whilst moving without issue just when it comes to a stop, I’ve tried google and on here but not a lot of info, anyone else came across anything similar? Just the fact the box behaves like normal whilst running is what is throwing me regarding the speed out put signal issue.

Just incase, the car is a PFL 4.2 4 speed

Thanks guys.