If my experience of this issue is anything to go by, then resetting your stereo will have no effect. The problem is a break in the rear wash/wipe hose around the boot lid hinge area where the hose leaves the main body of the car and enters the boot lid.

Every time you use the wash wipe, water will enter the void behind the vertical section of trim and give your electronics a free shower, therefore I would advise not using the rear wash/wipe at all.

I initially took my car to the local dealership who blamed the fault on one of the wash nozzles being blocked and blowing the hose connector off causing the water to enter the boot lid and flow down into the electronics every time I opened the boot.

They initially charged me £112 to replace the nozzle and when the valet guy brought the car to me at the reception he commented on the noise from the stereo…..enter one upset customer to the service manager’s desk. The manager I spoke to was very helpful and took it upon himself to carry out an inspection on the system personally and he called me by 9am the next morning to explain the issue. They then charged me about £30 (parts only, labour free) to repair/replace the hose section at the hinge.

Audi are well aware of this issue, yet they refuse point blank to cover it under their warranty program.

Apart from this issue, great car, 70k miles to date and ready for another 100k at least