I have a battery drain in my 56 plate A4 B7, Quattro, BUL, S-Line, Special Edition. I believe it had RNSE in it from factory (inc phone prep but not BT), however, when I bought the car it had a no-name media/ICE unit fitted (seller told me the original RNSE was duff & put in this substitute). I put in RNSE (genuine Mk II, 193G, H/W 05, F/W at 0650), which caused a battery drain overnight, around 10 hours with car locked. I measured a draw of 2.5 - 3A with a clamp meter & so I did what others have done on numerous posts & pulled fuses 1 at a time. My timing on pulling fuses to monitor current draw was rubbish so I didn't get to see it stop as I didn’t let the car sleep after locking. I wasn't sure if pulling a particular fuse would wake something else up causing false measurements, so probably not really a sound method of investigation. Turns out, after an investigation by a non-OEM auto electrician, it's RNSE causing the infotainment CAN bus network to wake up & drain the battery. As I understand it (reading the Bentley manual) B6 & B7 platforms don't have a dedicated CAN module & it's the instrument cluster that hosts the CAN gateway electronics. So, the sequence of events was that, after locking the car, the modules would eventually go to sleep after around 15-20 mins & only the alarm system was running (about 60mA). After around 10 mins, the RNSE was waking up & triggering the CAN infotainment bus in the instrument cluster but considering the current draw, it might have triggered the drivetrain & convenience buses as well, although, I didn't go into whether these buses were being activated or analyse the data on it. Monitoring the routine, all modules went to sleep after a certain amount of time-out (15-20 mins) & then RNSE repeated the routine & woke the modules up again after about 10-15 mins. Does anyone know if the CAN electronics on RNSE is a plug in module/daughter board that can be replaced or reflashed? If not, I'm not sure what to do about it as I can't find anyone who will look at this kind of fault. Most repairs are screens, buttons & disc drives, etc. Any ideas what could be causing CAN on RNSE to come alive every 10 mins - incorrect coding or wiring? When RNSE wakes up, would monitoring the data on the CAN Hi & Lo lines tell me what it's trying to do or what message it's sending out? Could it be the gateway itself waking up just because RNSE is connected? I think RNSE & the instrument cluster are coded correctly.