Interesting! I reckon the pedal potentiometers develop a dead spot, which the ECU can work around up to a point.....and then throws a code when it can't. I think in VCDS you can plot the pedal movement in the graphs section. You will see if there's a dead spot with that. Same thing happens to in-tank fuel pumps. Sometimes you can whack the petrol tank with a hammer, which will jolt the motor onto a different part of the commutator and hey presto, it starts!