I have an A4 (B6) 1.9 Tdi 2002. I went to work on Saturday & finished 8 hours later. I came out to the car to find the fan on. I went home (20 miles) then planned to drive up north. I found that the battery was so flat I couldn't unlock the car. I jump started the car & made the 160 mile journey with no problem however the fan came on approx 20 minutes after I stopped the engine. I've read some other forums & they were saying that this is due to water ingress into the ECU box & soaking the relays. Can anyone point out where the ECU box is & can this problem be related to the recent recall of B6's due to blockages in the plenum chamber?