My 2006 Volvo S40 has had continuing problems with alarm - triggers for no apparent reason in wide range of places and weather conditions. Volvo garage has checked it several times but can't explain or stop it. Now triggering once/twice a day and driving me mad. Any similar problems or a solution??

 

I've heard of it triggering on the older models because of a microswitch that senses when the hood is closed.

 

My Volvo S40 2004 has started doing the same thing. I try everything and it won't go off. I took the fuse for the alarm and locking system out this morning and so far it hasn't started again. It starts for no reason and will not go off no matter what I do. This is beyond annoying! Does anyone have any other ideas about this.

 

I have faced same problem.I have Volvo S40 which has 2 litre 5 cylinder engine , turbocharged, nice looks , good mileage etc , But i faced same problem.In this reason ,i will go to a expert in our local area who has vast knowledge tommorow morning and i think the problem will be solved.

 

My son has been having issues with his S40 alarm going off intermittently, and as an inexpensive troubleshooting step, I swapped the siren module out with a later unit from the local junkyard. ($4 and change). Looks like the same module is used until about 2013. (on S40 at least). No issues with sunroof or any other components at this time. Onboard battery seems to have a nominal voltage in the original unit, and the board inside the module looks okay. Without a scan tool, the task of locating a faulty intermittent component or input to the CEM, would be a painstaking job, and one that the car does not warrant. Only time will tell, if the alarm will continue its random acts of annoyance. In the meantime, I am adding some images for reference, for those who want to understand the nature of the beast. Good luck to all !

 

Make sure you turn yur lights to the off switch and let up the windows and sunroof if you have before exiting the car mine went nuts tday because I had left the lights on n forgot to switch them off

 

If the siren was going off, there wasn't any chance that the siren module itself was the culprit.

I'd suggest locking the car (arming the alarm) and then wiggling / jiggling the hood, doors, trunk. You might get lucky and narrow down the search that way.