Car Alarm

[daveessex]

Strange happenings:
Two weeks ago for no apparent reason, and literally 1 minute after I locked my Turbo S (991.1) the car alarm went off. I returned to the car unlocked and relocked it and again a minute later the alarm sounded, so I again unlocked the car, but left it unlocked. Shortly afterwards went for a lengthy ride to pick up my daughter from the airport.
So, 3 hours later I was back home, and put the car into my garage, connected it to my battery charger, it was now night time, and left it unlocked overnight.
The next day having disconnected the charger and drove the car out of my garage I locked it and waited, but no alarm. Used the car a little later, and was back home late afternoon. left it out of my garage and locked it. no alarm
Several hours later had a phone call from Vodaphone (yes on a tracker contract with them) to tell me the alarm was activated. Sure enough it had gone off, so put the car in the garage unlocked.
I booked it into Colchester OPC, and didn't use the car again prior to them collecting it yesterday morning (6th October).
The Service Team have called me twice since to tell me they can't fault the system, and more than strange there is no evidence on the car's log that the alarm has activated for the last 3 years.
They are keeping it over the weekend.
Any suggestions would be massively appreciated.

 

[TonyC911]

Lots of reports of the Siren units going bad on the 991.1 model :dont know:

 

[daveessex]

Lots of reports of the Siren units going bad on the 991.1 model :dont know:

Yes, have read this also about the 991.1 siren failing quite commonly during recent research

 

[ukrr]

Yep. My 2012 991.1 siren failed. Quite common but a super simple job to replace it - 5 minute job

 

[Luddite]

On acquiring my 2012/ 2013 MY 991.1 the alarm had not activated or caused problems, however as part of the 111 point checks the alarm siren was identified as having issues. My OPC fitted a replacement siren circa £300.

Apparently there is an internal and irreplaceable battery in the siren unit which requires the siren unit to be replaced when the battery nears the end of it`s life.

As has been mentioned it is a very simple task to replace the unit with a new one, and looks to be a one bolt and one plug to remove the old and replace with a new unit. As best I can remember it may just be a case of plug and play. I guess there may be a chance it might need coded in..?

There is a discussion on this elsewhere on the forum, so worth searching, also apparently the same siren is available for a lesser cost from alternative sources.

There are also discussions on alarm issues other than those which may be caused by the siren so well worth a forum search..

Hope you get it sorted soon.. :thumb:

 

[deMort]

I'll just add my vote to it being the Alarm Siren .. ive changed many on these and 981,s over the years for various issues including non start !

You wont get a fault code unless there is a communication issue with the siren .. in this instance i would expect its activating on its own .

 

[daveessex]

Update

Porsche Centre Colchester have now had my car over the weekend plus the last 2 days and nights when everyone it seems has tested the car, including techs taking it home overnight, and have reported formally that there is no fault, so I'm having it back today.

 

[mark pearce]

I ve had it happen to a couple of cars
Alarm siren, easy 5 minutes to fit a new one and no coding required

Demort is rarely wrong

It'll probably happen again next week

 

[nigel99]

I had same issue on my 2015 991.1 GTS.

Swapped the alarm siren and went away. They will all fail eventually when the internal battery runs out.

 

[deMort]

I'm not convinced it's actually the battery .. mainly as i often see original 996 sirens working just fine and they are circa 20 years old ..

Rather surprisingly .. the alarm siren is actually a control unit of sorts .. the Engine Control Unit ( DME ) is also one to give an example but that does rather a lot more lol ....

My feelings are it's a software issue .. mind you .. they have been superseded !