Hi possible faulty switch or motor housed within one of the door lock assemblys or a broken wire most likely spot for this is where the door harness is constantly flexed when door is open or closed. Your display/speedo unit might be able to show whitch door is at at fault as it will not show correctly if one of the doors is open failing this a vcds scan should isolate whith door mech is at fault. One of my a2s has the exact same problem vcds shows both front and rear o/s door mechs have problems and I am awaiting delivery of a known good rear one (due on Wednesday} but have been unable to find a drivers doof unit anywhere as I want to fit only oem units only. If you find that the drivers door is at fault (gets the most use) be aware that the mech is different on left and right hand drive a2s right hand drive part number is 8z 283 7016d
