Strange alarm problem

[Ant b]

Hello on my gti I ativated the alarm bleep a while ago but the siren was broke,so I fitted a new siren and all was well,
The last week on my weekly scan(decat)it said interior monitoring sensers,vehicle inclination senser and alarm horn,I replaced the senser (used) above the passenger door as I was told that has the two sensers in,but that made no difference so bought another used siren and fitted that and still the same,and I have reset the coded but there still there.
It appears that my interior sensers don’t work as if I lock the car with my in and move about my hazards don’t go of.
But if I lock it with the fob from outside and undo it with the key my hazards go of but no sound.
I don’t no if it’s linked but last week I did get a mysterious flat battery

[pudding]

Same errors on mine as well.   A common problem on these cars apparently.   I've never bothered to fix it because when they do work, they are known for falsies, and people ignore alarms anyway.   The immobilizer is the important bit, which still works regardless of the siren.

[Ant b]

It’s annoying me though,I liked my alarm bleep

[pudding]

Mine beeps in spite of the fault codes, but I hate it, so turned it off in VCDS 

[chigmuss]

I found that open grilles will see off the siren due to increased water / crud ingress.

[Ant b]

I’ve spoke to the seller on eBay for the siren and he’s going to send me a different one,maybe I the new senser and alarm are both faulty