I need some help to diagnose the root cause of the bizarre things that are happening with operation of the cabin electrics my 2003 Quattro Roadster. The story goes like this.
First the average fuel consumption started providing bizarre readings, jumping from 12 to 45 litres/hundred kms and then just rolling out wide ranging readings while the car was stationary with the engine running. All other dashboard information is perfect, except distance to empty, which varies with the reported average fuel consumption.
Next, the Bose audio decided it had lost power and went into safe mode. Since it was re-activated with the security code, about a week ago, it has worked perfectly.
Most recently the auto feature of the passengers door window stopped working, both up and down. The movement of the window was fine if the switch was held. This morning the auto feature was working perfectly again.
All this time the average fuel consumption readings have continued to come from another planet. The car runs perfectly and all other dashboard information, date and time, audio system information, average speed, spot fuel consumption, etc., including the test function appear to be operating normally.
I am concerned that a visit to the Audi Centre could result in a very expensive diagnostic effort without actually identifying the real fault. All ideas gratefully received.