Thanks for the advice, much appreciatedOn the A6 there is the eng compartment - a plenum in which there is the wiper motor and climate control which is covered by plastic - In the plenum are 3 drains one each side and one in the middle - when the middle one gets blocked water can come into the passenger footwell. The ECU is under the carpet as well as relays in the passenger foot well. The middle drain end can be seen from under the car.
A wire can be pooked into the drain hole/pipe/closed end from the plenum.