Mark999

I have lost the controls for Air suspension and Air conditioning from the MMI screen in my 2003 A8 4.2 V8 quattro. I have tried the reset function twice to no effect. Does this mean one of the control modules has gone down? Anyone experienced this and fixed it? Thanks. Mark Ewing

James - I can confirm the many switch and control lights never turn off. It did seem odd to me as why would you want them on when no one was in the car and it was locked - although they also stay on when it's unlocked. The actual instrument lights - speedo and tacho, etc, do turn off with the lights. I have located the fuse which relates to these tiny control lights and indeed they do turn off when it's removed, but the same fuse is linked to the folding wing mirrors and wing mirror positioning electronics, which I don't really want to lose. Mark

James - I allowed my battery to get very low - to the point where it wouldn't start - and after I'd charged it again the photoelectric (whatever!) drivers side mirror had gone from dark to light again, just as you suggested. Thanks for that. While I am on the subject of the battery, I have done extensive tests with a multi-meter, but cannot find anything that would account for the fact that my new 110 mah Audi battery loses charge at the rate of 0.6 volts per day if the car isn't used. Does anyone have any ideas what component might be responsible for such a drain? I have checked the obvious - boot lights, etc. There are about 30 tiny lights which illuminate switches all over the inside of the car - is it normal that these should be on day and night? Mine are. Mark

The light sensor on my 2003 Audi A8, after failing intermittently, has now stopped working completely. At the same time - and I am guessing the two things are connected - the automatically dipping drivers door mirror is now permanently dipped dark which means at night you can't see anything in it. (It beats me though, why the default setting for the door mirror wouldn't be 'light' rather than 'dark'). Oddly enough, this doesn't seem to effect the auto-dipping rear view mirror which doesn't work but as luck would have it has defaulted to 'light'. When I select the 'auto' headlights position a message appears on the dashboard saying that the 'light sensor is faulty'. Where is this sensor? Does it control the rear view mirror and the door mirror dipping function? Thanks, Mark

UPDATE to 'Garmin Satnav won't work in my A8' My A8 failed the MOT with a 6" crack in the lower passenger side of the windscreen plus one stone chip in the driver's eye line. Considering it is the original 12 years isn't bad. I had it replaced on insurance (less the £75 excess) and noted that the serial numbers were almost identical to the old one (M982 instead of M981) but without the Audi rings logo. Just out of interest I tried the Garmin Satnav in the car and to my amazement it not only found the satellites in seconds but continued to work perfectly on my journey, with no drop-outs as before the glass change.

What bad luck. I had this problem on a Renault Laguna and a BMW 3-series and in both cases it was the drain holes in the windscreen wiper area which were clogged with debris from trees. In both cars the water ingress was concentrated in the front, via the back of the dashboard, but water has a remarkable ability to follow along troughs and trim in the bodywork. I realise that this would not explain why your seats were wet, which would indicate the water was coming from above, perhaps dribbling along the headlining and depositing everywhere. I'd be surprised if there wasn't staining on the headlining if that were the case and from what you say it isn't that obvious. Mark

Based on your comment I just had a look at the windscreen and, apart from the fact that it is micro-pitted in a way I've never seen before (is this the solar-reflective giveaway?) it looks like any other windscreen. No filaments inside it or unusual components that I can detect. There is no nomenclature visible which would indicate what type it is. My car is the 'limousine' spec, which means that although it loses the potentially useful long load rear seat portal it gains a solar powered sun roof which blows cool air through the car when it's stationary - a gadget that actually works. Whether this could be interfering with the Garmin satnav I don't know, but it remains a baffling problem. Mark

I have a Garmin satnav which is much easier to program than the unit in my A8 and has the benefit of being 3D. The inexplicable thing is that the Garmin works faultlessly in my Fiat and my VW Transporter but in the A8 constantly loses the satellite signal. As nothing about the A8 is quite like other cars it doesn't surprise me but I am curious as to whether there are some radio or electrical emissions emanating from the A8 that would interfere with Garmin reception. It doesn't matter where it is in the car either, the effect is the same. I have driven the same routes in other vehicles, so I know it is the A8 causing the problem, not the Garmin itself. Garmin, never particularly good in the customer service department claim never to have heard of this phenomena and are insufficiently curious to make any suggestions. Anyone have any ideas? Mark

James, Yes I have checked for 'lights on' even to the extent of putting a video camera in the closed boot to see how long it stays on. I noticed that the tiny lights for some of the controls (not the mains instrument lights) were on at all times, so I pulled the relevant fuse for those. With those and the remote door lock fuses removed the battery went from a fully charged 12.4 volts on Friday to 11.8 volts on Monday with no use or extra charging. The loss is faster than this with the fuses in place, but I'm not certain these are the only draw on the battery. It still starts at 11.8 volts. I've found the lowest it will go without starting is about 11 volts. I would like to find the fuse for the self-closing boot motor and rear window demister - both suspects that need to be eliminated from the enquiry. Thanks. Mark

That's 7.5 fuses 41 and 39 for the front and back door on the passenger side. You may find that when you replace these the battery drains more quickly as the remote door locks can become faulty and use power searching for a signal from the key fob - at least this is what I've been told, and from my experience it seems to be true. The fuses you need are in the fuse box at the end of the dashboard, facing the door cards. There is one at each end. Also, my car has a drivers door mirror which supposedly 'dims' when bright headlights behind are detected. Mine dimmed on its own accord and stayed dim for 10 days before suddenly brightening again. In low light I couldn't see a damn thing reflected in it. I love my A8 but everyday I get into it I wonder what won't be working today - even if it starts working again when it's had a rest.

I am having a similar infuriating problem with my 2003 4.2 petrol Quattro A8. It loses enough power over three days of non-use to be unstartable. I fitted a new Audi battery. I have tried removing the fuses which operate the remote door lock sensors (they also cover the door mirror operation) plus the fuse for the instrument lights. This was based on what I'd read elsewhere. Still the battery drains. The next thing I thought about trying is the alarm, sited in the engine bay as I understand the batteries can rust and cause a power drain - but this is only guesswork. I have a Ctek intelligent battery charger which I have to use on the car every few days if I'm not driving it much. It would be impossible to leave this car in an airport car park for even a week as it would be completely dead. I would love to know if there is something I've overlooked that is causing such a substantial drain. My auto-opening boot doesn't work but I can hear the motors clicking and whirring. I thought about removing the fuse for that to check it, but according to the manual it doesn't have its own fuse, so I presume it must share one with some other function. Anyone know? I guess it's a question of just trying everything until you find the cause. Do let me know if you do.