My Vectra (02) Mk2 model, the alarm occasionly goes off despite my conciously ensuring that it has been correctly set for no apparent reason, one of my neighbours has the same model and has experienced the same problem, So is it a common problem? Any ideas as to the cause?
possibly a fault with a microwave sensor. they sometimes fail internally. the sensors believe they are picking up movement but they arent. would take it to a specialist dealer though.