Constant open zone, faulty sensor?

Overleaf

My mother has a hkc quantum installed in her house, when arming the alarm it keeps saying one window is open when it's closed. I changed the battery in the sensor, initially it appeared to not do any good, but after a day or so it started to work normally again. After about a week of it working fine it's back to saying the window is open, does it sound like the sensor needs to be replaced or is it something else?

Thanks

altor

https://www.boards.ie/discussion/2058287829/constant-open-zone-faulty-sensor

Yes, it could be the reed or the shock that's in the sensor.

If its the shock you can get replacement heads. The reed is built into the device but you can disable and add a wired one.

Overleaf

https://www.boards.ie/discussion/comment/120354795#Comment_120354795

Cheers, I never got round to this. Apparently it will trigger the alarm off even though it's not armed every so often. I might just replace the sensor unit, do I need to deregister the old one and add the new one or what way does it work?

Thanks