PaulColl

I have 2004 Legacy 2.0 auto which is getting long on the tooth, but has generally served me well. However, these past few nights I have found that if I lock up the car with the IR button on the key, some hours later the car starts emitting a siren noise for about 15 seconds off, then fifteen seconds on, for up to five minutes. No indicators flashing - just a siren. If I try and unlock the car, this works, but the alarm still sounds. I can even start the car and drive it around - with the siren still going, so as well as no flashing lights, this siren noise is not associated with the immobiliser function, either. On the first night it happened, I hastily got a torch, flipped the bonnet and removed the +ve connection from the battery - I could see no other way of shutting the car up! This resulted in the car running very badly the next day and stalling for a few hours - I believe this is because the engine management has to 'relearn' the engine's habits. Does anyone know what this issue could be? At present, the only option I have (other than to disconnect the battery) is to leave the car entirely unlocked overnight. Not ideal!