996 false alarms? (OEM alarm)

I'm having problems with my 2000 996 coupe's alarm going off. It's happened maybe six-seven times over the last 5 months. Usually it's happened when the car is under a parking deck at work but it's also happened at least twice while outside the deck. Curiously, it has NEVER happened at home- in the garage or outside. It's not an exterior motion-sensor issue, as far as I know. One eye-witness said no-one was even around the car when the alarm went off. And pushing on the car won't set off the alarm, either. Anyone have any ideas?

any chance something is not shut 100% and somehow pops open over a bit of time (ie, the hood, oddments compartment or gas door latch) The alarm is tough to set off by accident. I have only had mine go off once and it was when I reached thru the window on a nice summer day to get my sunglasses out

I don't think so- I did have to re-adjust the front hood latch, which was sticking when I bought the car. So, I'll take a look at that- but it has never popped up or un-latched that I know of. It's just really curious that it has never happened at home. The false alarms do seem to occur after I have driven it fairly recently- i.e. to work, after returning to work from lunch, at the dentist.

I read one guy had a problem with the IR sensor for motion detecting had a problem so it would set his alarm off. If you are ever getting the horn bleep and double flashing light for soemthing isn't secured then track down what is causing it. I didn't get the center console box closed one time and have had stuff over stuffing the door compartments that I think was giving me an error. I'm just imagining if the temp changes it changes the gaps on things like a loose fitting alarmed area might have. Hopefully it isn't a hardware error happening.

yes- it's the horn beeping and flashing lights. does that indicate an IR alarm? and is IR just an inside motion-detector? or does any latch-type alarm (hood, doors, engine cover) also result in horns/lights going off? My '00 doesn't have a glove box. But I do have a locking center compartment (behind hand brake), that had the hinge replaced before I bought the car- so that could be the culprit. I never lock it, though, so that should not be it (unless there is a short or something). I doubt the side door compartments are alarmed (mine cannot be locked), but let me know if you know otherwise. Thanks for the replies.

If there is something not secured you will get one beep of the horn and a double flashing red status light. It's not the alarm going off but an indication that something isn't secured for the system to fully arm. I think that center console compartment is possibly one of the alarmed sections. I know I have messed with the car popping the hood and engine compartment then never gotten into the engine compartment then had the alarm problem. The engine lid will look locked and there is no idiot light for it being open but it wont be secured. So I imagine it has a tight tolerence that could go either way with the alarm unit reading its status. That same engine area has heat then coold which changes gaps. Could be that area where your alarm sensor gets triggered from.

As my dad used to say, "When all else fails, read the owner's manual." (and Rennlist). I am having the double-flash and a single horn beep when the alarm is set. Per the manual (and post above), the double beep indicates that not all locked areas are secure. This happens (for me) even when the center locking console is locked. I also recall that when I bought the car, for the first 2 months or so, there was NO beep (at all) when I alarmed the car remotely. Then out of the blue it started to get the single beep when remotely alarmed. which I thought at the time meant the alarm was working. Now I realize it probably means that I somehow disengaged the lock when adjusting/fixing the fron hood latch. So, that is probably my culprit. But it will have to wait for warmer weather before I attempt a repair. Thanks everyone for leading me in the right direction. QUESTION: do you guys get NO beep when you remotely alarm your 996?

no beep (unless I leave the center oddments tray door open )

Has there been an aftermarket stereo installed? If so the alarm contact needs to be modified.

It may be possible that someone else is setting your car alarm off while trying to open or close their car with their remote. It shouldn't happen but I've seen stranger things happen. The key here is that it never happens at your home but only at work right?? Although they have a rolling feq as a lot of other remote systems have, such as garage door openers and remote car starters, it IS possible that interference from other devices (iPhones?) could be at fault here and not that something isn't locked on your car. With all of the devices we have in play now that use wireless bands, it wouldn't surprise me one bit. It's one of the reasons why Boeing and Airbus spend so much time and money on shielding... so some dimwit like me doesn't try to open his car and one of their aircraft flying overhead has the no smoking lights turn off or the gear drop uncommanded. CC: Toyota

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That guy may have been me. I believe my problem occurred when I placed a flimsy sun protector against my windshield on the inside. As the car heated up the metalic coated protector expanded, moved and triggered the motion detector.

Problem solved (thanks Robert, above). it was the aftermarket radio. I pulled it out and after numerous attempts to discern which wire was causing the problem, it turned out to be a brown wire with green stripe (there is more than one). But here's the kicker- the aftermarket radio I installed has a metal chassis or "carrier" that fits into the vacant radio slot before you insert the new radio. I had to pull out the new radio AND remove the carrier/chassis to get to the correct brown w/ green stripe wire. If you don't remove the carrier/chassis you won't see the culprit wire. It is connected by a spade clip onto the left-hand side of the vacant radio slot. Pull that spade clip and tape it off, and that should do the trick. It's been fixed for over a week with no false alarms.

Glad you are all fixed up. Now you can cruise to Nags Head or some place fun without false alarms The Black Pelican was a nice place to eat when on a 4 day pass from Bragg before a long romp in opium fields. Pinch a waitress for me They have a wide assortment of t-shirts with their logo too. I liked the long sleeve ones.

Sorry for digging up an old thread but I'm having the same problem with my 2001 996tt. I recently put an aftermarket radio in my car about a month ago and since then, I have noticed my alarm going off by itself on several occasion. So just to clarify - was the solution to remove the alarm brown spade clip from the metal chasis of the aftermarket radio and tape it off. Right now - I have it plugged to the metal chasis. Please advise. Thank you. Kiet

I did the opposite with the wire and attached it to the chassis. When I tried taping it off I got the alarm fault.

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Yes brown wire should be taped off. If its attached in factory location, you might just be able to pull off the left side panel with the 3 switches to access it. If this is the case, it should be a 2min fix.

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DCNSX, I too have an after market radio in my 2002 996. I also have issues with my alarm going off in-frequently and I have been told it is my aftermarket radio. When you mention that the culprit wire is behind the "metal chassis", are you referring to the metal case that initially installs first in the vacent stock radio position that the aftermarket radio slides into? I ask, b/c my aftermarket JVC (KWAVX840) call this the "sleeve" and I am hoping that, that is what you are referring to. Also, the culprit brown wire w/green stripe, you pulled the spade clip and taped it off, should that wire just remain free or does it need to be connected to some other wire that is part of the new aftermarket radio? I am hoping that your solutions is the same for me, it is very frustrating, and none of my mechanics have been able to figure it out (not the Porsche dealership, nor my Porsche mechanic). Thanks for all your help!

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thanks for the tip. It really was a 2 min fix and you didn't have to pull out the radio. No more beep on arm and false alarms!

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Hi Robert944h and Alpine003, thanks for that great tip. I successfully installed an aftermarket Pioneer double-DIN AVIC-F88DAB in my '99 996 C4 Convertible (CAB) as a replacement for the OEM Porsche CDR-22 radio, including more bells and whistles (disconnect the OEM HAES 6-channel amp, doing all the rewiring, JBL GTO front/rear speaker modification (4x), JBL GTO 16.5 cm speakers in the doors, Alpine aftermarket 300W ampilifier to drive the door speakers/woofers, DAB+ digital radio, up-to-date navigation, wireless Quickcharge 3.0 enhancement etc.) Since taking the new unit into operation (everything's perfectly fine in terms of the operation of all audio/nav functions), the alarm went off at completely irregular times (typically it took multiple hours, but after resetting it, it kept going off every couple of minutes or so) for no apparent reason. Just minutes ago, I have disconnected the brown-with-green-stripe wire (that obviously previously needed to be connected to the chassis of the OEM Porsche radio that the double-DIN Pioneer was replacing.). Now I still need to test things out for a number of hours/days from now, but let's agree that if you do not hear from me again stating otherwise (I may forget to explicitly report back whether this was the fix....), you may all assume that this was the actual fix for the intermittent alarm issues in my case as well. And yes, I can confirm Alpine003 in stating that this was a '2-minute-fix'. Once the left side panel was carefully removed, removing the connector (with the brown-with-green-stripe-wire) from the chassis was quite simple, gently pushing it to the back and off the chassis.

^^ In case you didn't notice, Alpine's reply was from 6 years ago - so if he doesn't reply don't be surprised! I hope this fixes your alarm problem...

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Thanks dporto. In fact, I did notice this thread's age, but since the 996 (and any audio or other upgrades to make it even better) are never out-of-fashion, I decided to share this info with the community, so that it can help anyone facing a similar problem. Thing is, one can search for hours/days/weeks to find solutions for issues like these, so the '2-minute fix' is always benificial to our own state of mind, but also retains the tranquility of our neighborhood.... BTW: So far, things are going fine with the alarm. That is, no unneeded alarms for 2 hours now, let's hope it stays that way, time will tell.... QUICK UPDATE 18th of june 2019: Since disconnecting/taping off the brown-with-green-stripe wire last week, NO false alarms have been produced by my car. Not a single one. The car has been parked in 'fully armed alarm mode' for multiple days. As such, this solution definitely can be considered the structural solution for this issue.