power door lock problem
 

A problem suddenly happened the other day. all door locks seems not working any more... I press the lock button on master key, the red LEDs by the front door windows flash, a horn will confirm all door are locked, but actually none of them can lock. and a strange little motor sound came from the trunk by the fuel tank cap. confused... Please help.

your locking vacuum pump is dead. You need new one or second hand one that works. Theres a carbon disk inside it that brakes in time and if you scan the car with VAG-com you get an error saying something like "vacuum pump signal intermitent" "possible cause leak" . Its a knows B5 problem.

A new one costs alot and you have to reprogram your keys to the new unit. You can also buy a used one and replace your pumps broken/shattered disk with that one so you dont have to reprogram keys.

I have it also but its still working...but i get the vag error. I give myself 3 more months untill total error :D .

The pump is located inside the trunk right under the taillight near the fuel cap :) . It sounds like grinding coffee. Remove the lining and you will find it.

Good luck :)

Find the pump like weaselciuy says, pull the vacuum connection off of it, then put your finger on the nipple the vacuum connection was on. Hit the lock button on your key. If you feel suction, you have a leak in your system somewhere. No suction and pump motor noise? Pump's shot.