Hi - hope there's not already a thread on this - I cant find a "search" function.

So: problem is a Golf Cabrio 1999 which suddenly developed an immobiliser alarm fault. The car's not immobilised at all but the horn and lights go wild when I open a door or switch on the ignition UNLESS I have in the previous minute or so unlocked (or re-unlocked) the car. It seems to arm itself automatically a minute or so after unlocking (even though the car remains unlocked throughout).

Garages wantto strip down the doors and look at the wiring - but this seems unlikely to me to be the solution and sounds expensive.

Any ideas please!?