Central locking failure - help please?

[KarenM2013]

Hi, I'm new to this site and to VWs, so really hoping someone can help me please. The central locking is working fine on all doors and boot apart from one rear passenger door, in that it won't lock all of a sudden. Using remote and key will lock all doors but the affected one will immediately unlock again. I've also tested with the interior child lock button and it doesn't work on the one door either. With a young child, this renders the car unusable until I can get it fixed. Please can someone advise on likely problem (mechanical/electrical) and best approach to getting this fixed before I resort to costly dealership support? Thanks so much. Ps I didn't close the door properly overnight on Sunday which may have something to do with it...

[alexperkins]

That's normally a sign of a fault in the door lock mechanism. The car needs to be scanned for faults really to confirm it.

[KarenM2013]

Many thanks for the swift and helpful response. I should mention that when I lock the car - it's the usual 'two click' sound followed by an extra immediate 'unlock' click on the affected door. Final question then, unless further advice is on offer, should I be off to dealership for diagnostics or a regular garage/auto electrician? I'll post outcome in case it's of help to anyone else who has the same misfortune some day! I really appreciate the help, what a friendly forum.

[alexperkins]

Thats a sure sign theres a lock failure - the locks send a 'confirmation' message back to the cars computer. If they dont lock successfully, the car will automatically unlock the affected door again.

Its really off to a dealership for investigation - if its under warranty this would be covered.

[KarenM2013]

Thanks Alex, you've been massively helpful and what you say makes sense. Can I trouble you with another one? Where mileage should display on dashboard is showing up as 'error' as of this eve. I was stuck in traffic and out of boredom, without realising, was pumping on accelerator whilst out of gear and handbrake on (not revving!). It showed up after that. Online research suggests that this can trigger 'error'' - any idea how to fix/reset?

[alexperkins]

Have never seen that one im afraid - thats a question for someone else in this instance