Sounds like it's not uncommon to have alarm problems and I've just bought an S40 which does! I bought the car yesterday and the alarm went off several times in the night. The battery is good (and looks new), but I don't know where the sensors are, is there a description of them all and which is a likely culprit? Can I disable the alarm? Thanks James

Have you got a mobile phone or blackberry in the car overnight ? sends my alarm scatty, Indeed you should have a button, simply turn the ignition off but don't remove the keys - them press the button on the left of your heater knobs (looks like alarm from a car) which should light - turns all internal sensors off for dogs - and misfunctioning sensros alike... cheers

Have read here. I am guessing our problems will rear their heads when it gets to Winter!

T4Viper - No GSM devices in there but that's interesting, must be very sensitive then. I'll have a look for the button but don't remember seeing it manoman - thanks for the link, was looking through that earlier

I don't mind which thread we problem solve in, but would be easier for future if we keep it in one place? At the moment (touch wood), since charging the battery using the Optimate and cleaning the bonnet switch I have had no more problems.

As mentioned, I don't think it's the battery on mine. I checked for a button on the dash but no joy there. I did find an interior light was on this morning so I'm going to see if it makes any difference tonight Does anyone know what volvo use to read out the last 10 causes?

check switches 

check that there is no crud on the bonnet switch, it is a common fault. you state that the interior light was on? once again, check your interior light switch on each door is cancelling when the relavent door is closed. paul

Thanks Paul, The switch next to the sunroof controls was the cause of the interior light, both doors seem to actuate properly. I'll look for this bonnet switch later Cheers James

OK so it wasn't the interior light but locking the doors with the key stops the alarm activating so that will do for now. I think I may invest in an OBD reader and pull out the cause that way