What tells the car that a door is open?

[searider]

Sometimes the dashboard display tells me that the drivers door is open when it isn't!

Is there a switch in the door that might be a bit dodgy.

Can't see an old fashioned plunger type switch in the door shut.

[Philws4]

AFAIK the switch is built into the door catch and can only be accesed with the door trim off. Might be worth spraying some WD40 into the catch and opening/closing the door quickliy a few times in the hope that it frees it up

[PetrolDave]

AFAIK the switch is built into the door catch and can only be accesed with the door trim off.

Correct.

The offical Audi position is that you have to replace the whole catch when the micro-switch goes faulty (they don't sell the switch separately) but several people I know have been able to adjust the switch and get it working again. Cost = zero, just some time to get the trim off the door and remove the lock.

[neckarsulm]

Maplin electronics sell these microswitches too.
There is a US thread on the web somewhere - bloody stupid idea!