Auto box problem

[V8-108]

Right, first off I'm not sure if mine is a B5 or B6....what's the difference please?
Anyway, what I have is a 2002 A4 Avant 3.0 Quattro auto, and there may actually be more than one problem. First off, and most annoying is that very often (almost always, and especially just after starting) when I select reverse the gearbox goes into limp mode and I need to switch off and start the car again to get rid of limp mode......after this it drives ok in D......until I select reverse again, then we are back to switching off.
The second problem (probably/possibly related) is that the tiptronic doesn't work ( it might sort of have a go at working occasionally) It usually doesn't light up in the dash, and simply doesn't work on the gearbox. Sometimes it flashes between tip and auto on the display as though it's trying to go to tip, but seems like an electrical short or something.
Lastly, and again probably related, is that sometimes the changes in auto are not as smooth as I would expect (had an A6 2.8 Quattro in the past) especially when slowing down and the car goes into 1st......it can be quite a "clunk" as it goes in.
I am aware of some of the problems with water getting into the transmission ECU and have to admit that it is wet under the drivers carpet but not got enough of it up to be able to check the ECU ( provided that's where it's located?)
Is this the most likely cause of my problem? Will it be able to be dried, or likely to be trashed?
Also, I have looked at the circuit board under the gear lever, and this may have a fault too as the tiptronic + and - LEDs only light up bright (in tip mode) when pressure is applied to a certain point......might this have something to do with the problems?
Sorry for the long post, but wanted to give as much info as possible to be able to narrow down the relevant info I might receive back.......thanks in advance for any help.

Neil

[fourringsrus]

You need to get the car scanned with vagcom/vcds to highlight the problem, your car is a b6.
The b5 ran from 95-2001
b6 2001-05
b7,mid 05- 08
b8 08- current

[Mikey1756]

Hi
My a6 allroad is having the exact same problem started just on thurs, its going in to the garage to get scanned for faults tomorrow.
have you got this problem sorted yet?
I have done some googling and most say ECU fault,

i'll let you know after the garage.

cheers
mike

[V8-108]

Right, further information on my ongoing problem. I have had the codes read, and there are a few, mostly connected to malfunction of the TCM. My mechanic (someone I trust) has been in contact with the Audi garage and they have said that the most likely cause is ECU or gearbox internals.
My problem seems to be temperature related as after driving for a while and getting the car to temperature, the gearbox seems to work almost faultlessly......selecting reverse doesn't send you into limp mode and the tiptronic works pretty much fine. We are beginning to think that, as there is no evidence of a fluid change in the vehicle history, that we might just get some sort of result by changing the fluid and filter in the box. The thinking is that the fluid becomes more viscous as it warms and runs through the valves in the box much better giving better performance........we may be way off the mark, but as probably the cheapest thing we can try, we might just give it a go.......what does anyone think??
Neil

[fourringsrus]

Theoretically it sounds like a good way to go, but bare in mind that the amount of fluid and its type , will not be cheap once added to the time and procedure involved and that you might well have to do it all again, if unsuccessful, if you have to dig out the ECU.
Thats what I was told with mine,...3.0 petrol quattro tiptronic 2002 A4

Stuart

[V8-108]

I am aware that there is a fair cost involved in something that is, at best, speculative, but it's the cheapest thing I can do as a first option. If it has an effect then good times, but I am all too aware that I could be quite a bit poorer and still in the same place! I suppose it's going to be something of a "suck it and see" scenario as we work through progressively more expensive options to sort it out......probably ending up with the most expensive option and having wasted a load of money getting there! Anyone with any further thoughts or experience are more than welcome to add their thoughts.

Neil

[pauldazzle]

Do a fluid & filter change with genuine VAG stuff. Temp related auto gearbox problems are often caused by old burnt & thin ATF. It's worth a shot & much cheaper than the other options