The rear passenger door (drivers side) wouldn't unlock today on my 08 A3 with the keyfob, but was fine if opened from the inside.
I've had a look around on the web and see its a common problem. However the symptoms listed on here and other forums don't quite match what I am experiencing.
I tried the various techniques listed but none seemed to work. So I started to have a fiddle with a screwdriver in the latch and noticed the mechanism seemed a tad sticky. So I added some grease and WD40 and it eased up.
After this it seemed to work better but its still erratic. Sometimes it opens, sometimes it doesn't. If you try to open the door while it is locked I can guarantee if you unlock the car it will refuse to unlock if you then click the keyfob.
When it does unlock you hear a satisfying click as opposed to a weaker click if it does not unlock.
So is the mechanism still sticking due to poor lubrication, is it a dodgy motor or is it the dreaded cable problem inside the door?
The reason I ask is because if it is a motor or relay in the central locking system, my car warranty covers it. Any other issue and they'll sting me. So I want to diagnose this myself without causing any further damage just in case I can get this repaired for free.