Hi, I have browsed the forum and google for solutions but could not find anything directly relevant to the problems I experience. I am hoping someone here will be able to help? I am giving a precise description below, which I hope will encourage the fellow forum members to a valuable response...

THE CAR:
A6 (C5) 2003 avant sport 1.9 TDI - UK version (right hand drive)

BACKGROUND:
The car was left for 10 days undriven while I was away for xmas. When picking it up from the airport I could not open via key fob and opening drivers door with the key does not open other doors. Passenger door and rear doors cannot be opened from the inside either and alarm goes off as soon as the driver's door are opened by inserting the key.

THE PROBLEM:
a) I investigated a bit more upon my return from the airport. Initially I thought the fob battery went flat so I tried the spare key which has worked in the past - but with no effect.

b) When turning the key to the right in driver's door only that door opens (button goes up). after physically opening the door the alarm goes off and can be only disarmed by turning the key in the ignition.

c) All other doors can't be opened from the inside: when pulling the inside handle the button goed up but as soon as the handle is relased the button goes back down (pulling the outside handle when the button is momentarily up does not one the door either).

d) I can't disarm the alarm by pressing the button near driver's door (the LED does not switch on when the button is pressed).

e) The central locking 'lock'/'unlock' button on the driver's door does not function. When pressing the 'lock' I can hear the door solenoids closing the already locked doors but the 'unlock' does not provide any audible feedback.

f) Other observations: the battery voiltage is correct 12V with ignition off and 14V with alternator running. When opening/closing the door by turning the key in the driver's door the indicators do not flash as they would if the central locking was operational.

g) I have been reading the central locking threads on various forums and found out that the central locking unit often is subject to excess moisture and connector contacts tend to oxidise which can casue malfunction of the system.

QUESTIONS:
1. has anyone came across the particular problem when ALL passenger doors stay locked even when the key in the driver's door is turned (that indicates a general fault of the centra locking unit, not a fault of a single lock). Did you manage to fix it yourself? If not what's the cost of fixing by a garage?

2. WHERE is the central locking unit located (UK right hand drive)? How do I get to it? (any instructions would be helpful). I am an electronics engineer and I suppose I can investigate the problem and attempt a repair before taking it to the service.

3. If I find that the central locking module is irreparable, what is your experience with replacing the module? Does it need to be re-coded, can it be done by myself or only by the service?

4. Can I learn something about this problem from OBD-2 connection by hooking up the VAG-COM cable? I have a cable and software I used in the past on my previous A4 but I do not know where is the OBD-2 socket located in the A6?

 

I have quite serious problems with my vehicle too. I find it very strange that nobody reacted on your mail, as it appears to me that it is a very common problem on this model range.

Disappointing reaction!

 

Check under passenger & drivers side carpets , see if there is moisture under there. If it is wet you most likely found the problem.