Temperamental door lock that works when knocking!?

[shure2]

Hi guys,

The back door on my Fabia locks very temperamentally.

When it doesn't unlock I can't open it from the inside or out (child lock obviosuly disabled).

When I sometimes fist slam (pretty hard) on the left of the handle on the outside as I press the central locking button the door gets power and unlocks. I might then be able to lock and unlock the doors but it can happen again.

It just failed its WOF (MOT) because the mechanic couldn't open the door.

I'm thinking it could be an electric problem as I believe a bit of water has managed to get in the door.

Any ideas? I was told by the previous owner it works better when it's warm!?

Edited 2 August, 2015 by shure2

[trundlenut]

Dodgy microswitch or lock needs lubing up.

Sent from my D5803 using Tapatalk