Car alarm keeps going off...

[TheCarFather]

It's a Punto Evo with a cat 1 thatcham alarm fitted, I am having to resort to leaving it unlocked so that it doesn't go off all night, have triple checked all doors, tailgate and bonnet and there isn't anything moving in the car. When I look it the normal bleep doesn't happen but the car still locks.

What could it be? the car has a warranty will this cover it? thanks guys.

[Rich_W]

This sounds exactly what warranty is for.

Possible alternatives. Siren built in battery dying. Or water ingress into a component

[Matt UK]

My vote is battery.

[TheCarFather]

Matt UK said:

My vote is battery.

They did say they gave the car a new battery before I bought it since the battery was dead, could they have not wired it up properly or something?

[marmitemania]

I think it would most likely be a faulty movement sensor in the car, this is quite a common fault with lots of car alarms. Either way if it has warranty it should cover this.

[TheCarFather]

Thanks everyone

[P I Staker]

In the mean time you can probably lock the car with the key in the door and it wont arm the alarm.

[JimbobVFR]

Sounds like it could be a dodgy door,boot or bonnet switch to me.

I had a similar thing with my Audi A2 after an accident repair. It needed the catch on the bonnet adjusting slightly in my case. I've also known a failing switch to caiuse the same thing on a previous car.

[160]

there was a well documented issue with the 'grande' punto for the boot door switch, the best way to test it is to see if the boot light turns off if it doesn't when the boot is closed then the switch has failed. If its the boot switch you could strip it down and dry it out and it would usually work again.

[TheCarFather]

Thanks everyone, the alarm even sounded after locking with they key in the door so I had to leave it unlocked tonight, would I get a courtesy car whilst they are sorting mine out? (apologies if that's a daft question, I just haven't had a car from a proper dealership before) thanks.

[Tuvra]

I had a similar issue years ago with a Volvo C70, rang the dealer who said "you probably have coins stored in the compartment below the radio, empty that and let us know how you get on".

Sure enough it sorted the problem, apparently they interfere with some sensor when stored here. May be worth emptying the car of all junk etc?

[TheCarFather]

Tuvra said:

I had a similar issue years ago with a Volvo C70, rang the dealer who said "you probably have coins stored in the compartment below the radio, empty that and let us know how you get on".

Sure enough it sorted the problem, apparently they interfere with some sensor when stored here. May be worth emptying the car of all junk etc?

No junk in the car really, apart from a small-ish metal box that is in the boot, couldn't be cause of that could it?! I put it in around the same time the alarm started happening, strange. Will check in the morning when I take the box out, thankyou.

[TheEnd]

The majority of cars these days store alarm triggers in the fault memory, not always faults in the usual sense, but for cases like this.

A scan should show what is triggering it and that'll make it an easy fix.
If it doesn't have a memory like that, there usually is a set of flash codes it will show after being triggered that should say what set it off.

[22Rgt]

Mouse nest inside the car, thats what it is, theyve come through one of the many holes in the floor..