my vauxhall astra 2002 mark 4 sxi 1.8 z18xe has recently developed a what i would call an electrical fault basicaly it first started with the battery going dead over night or with in few hours it varies so i put a new battery on still same problem only now when u turn the car off and take the key out the ignition lights and dash/centre console wont turn off they get dull unless left for while then they flicker and fade off and on so now the only way i can get them off is buy disconnecting the battery my friend got code reader from his work and it brung up 4 fault codes they are p1530 A/C Relay Voltage High Air Conditioning System B-10 p1530A/C Relay Circuit Open Air Conditioning System B-10 P1540 Air Conditioning Pressure Signal High Input Air Conditioning System B-05 P1540 Air Conditioning Pressure Signal Low Input Air Conditioning System B-10 P1540 Air Conditioning Pressure Open Circuit Air Conditioning System B-05 P1540 Air Conditioning Pressure Invalid Signal Air Conditioning System B-10 P1612 Immobiliser No Or Wrong Signal Immobiliser C-05 P1613 Immobiliser No Or Wrong Signal Immobiliser C-05 i have just replaced the ignition barrel as we thought it was this but still the same problem first turn car wont start second or 3 time it starts and runs perfect with no other problems aparts from the car with spanner through it light on and the eml light.could this be an alternator fault as i am starting to get fed up with trying to figure this problem out and dont want to pay 100+ for new ecu kit or garge bills if i can help it if it ends up not being the ecu lol any help or ideas would be very help full p1612/1613