Can any body help with my strange alarm fault. I have a 53 plated zaf 2.0 diesel and i have an intermittent alarm fault which only sounds the siren not the horn and doesn't flash the lights. It only happens when the engine is started so it doesn't affect the immobiliser. I've just got back from my vauxhall dealer who plugged it in but found no fault code. Any advice would be much appreciated..