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A new problem: Every time I lock the car, after about 30 seconds, the hazard warning lights start flashing at normal speed, as though I hit the switch on the console.  Other clues:

- there's a fast ticking from behind the gas-cap - faster than the flashing cycle.  Is that where the rear BCM is mounted?  It's louder inside the car

- the rear tailgate lights come on solid - the ones that illuminate below when the tailgate is open, they're on inside the car with it closed

- unclearable fault on the BCM rear with Durametric

  3615 / E1F
Warning Indicator On
...(usual test not completed blurb..)
Fault Active

- door LED double flashes "bli-blip....bli-blip" instead of typical "blip.....blip" (hope that makes sense)


What I have done so far:

- This was happening Thursday, Friday I bought a new, correct Bosch AGM battery and replaced the Mercedes wet-battery that was in there (why don't people get the right parts??, it's not like Mercedes parts are cheaper...)

- cleared codes in everything else I could find (used to be two in BCM rear, but above one will not clear)

  - I see codes in FL door/FR door  (something upper-limit exceeded) but Durametric crashes when I try to clear them

  - Also codes in front seat (upper-limit exceeeded) but again, Durametric crashes when I try to clear

 - car didn't do it all weekend after initial code-clearing session and new battery - didn't drive Monday, drove to work today and it's doing it again. 


Problem is, I unlock the car, it stop, car self-re-locks after 60 seconds, fault recurs.  Just once in the night it also made a quiet sort of wailing beep - I've never heard the alarm go off but if this was the alarm, it's pretty quiet. 

Thanks for any suggestions. 




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Suggestion - find someone local with a competent Porsche diagnostics tool and find out what the codes are that Durametric won't read. I'd suggest iCarScan - but I'm biased - I like it a LOT more than my Durametric and find it much more competent and complete.

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BTW - is the gas door locked when this happens?  Just wondering if a failure to lock the gas door throws a failure warning that the vehicle lets you know about by dancing around with the routine you've described.

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3 hours ago, deilenberger said:

Suggestion - find someone local with a competent Porsche diagnostics tool and find out what the codes are that Durametric won't read. I'd suggest iCarScan - but I'm biased - I like it a LOT more than my Durametric and find it much more competent and complete.

Thanks again Don.  Yeah I'm confused by the Durametric at the moment - 2 reasons:

- no way of understanding the codes - google them and find no info at all - do you mean with a different tool it might interpret the codes for me?

- communications failure when I try to clear, for instance, the door or seat codes. Then have to re-start the software etc. (and tell it AGAIN which Porsche I have and that it's a V8)

I've only had it a month, do I really have to buy another one? :-)

To answer your other question, yes I'm pretty sure the fuel-flap is okay, I've tried locking with it open, closed, pressed it had shut etc - seems to be working fine. 




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Hi Richard,


Well, I haven't been to Santa Cruz since June (by motorcycle..)  if you wanted to drive to NJ - we could hook it up to my iCarScan and see what happens.


The symptoms you're giving make me think the alarm system is reporting something unlocked - and letting you know with the funny door LED flash and the 4 way flashers.  That's where a good diagnostics tool can be a lot of help - it can check each sensor and see what the body module thinks the state of it is.


I'm going out to the garage to try something..


Back, lets see if I can remember what I saw:


  • Normal operation - all doors closed, gas door closed - hit lock on the key, the LED on the door flickers, two chirps, then the LED flashes rapidly for 20 blinks (about 1/sec between blinks) then it switches into a slower blink mode (maybe 2-2.5/sec between blinks.)
  • All doors closed - gas door open - same as the normal operation. It seemingly ignore the gas door.1
  • A passenger door partly latched - LED comes on solid for about 10 seconds, followed by pairs of blinks - about 1/2 second between the two in the pair, and about 2 seconds between each pair.  So blink-blink, 2 seconds, blink-blink.  No parking light flash, and no chirp.
  • Drivers side door partly latched - it simply doesn't lock at all.

What I didn't try is keeping the latch on the gas door from fully extending to the lock position - and my WAG is - that might be your problem. Since it doesn't care if the gas door is open or closed - it isn't monitoring the gas door position, but it might be monitoring the latch state of the solenoid that latches/locks the door closed.


Just checked the manual - the rear body-control module is located "RIGHT SIDE OF REAR COMP" - but it has several outputs to the "TRUNK, TAILGATE, FUEL DOORS SYSTEM".  Looking at the diagram for that circuit - the FRONT BODY CONTROL MODULE actually controls the ACTUATOR TANK COVER OPEN and ACTUATOR TANK COVER CLOSE outputs - which are interesting since there are just these two leads going to the TANK COVER ACTUATOR - no ground shown.  That makes me think they reverse the voltage going to the actuator to have it open and close. The FRONT BODY CONTROL MODULE is located "LEFT SIDE OF DASH".


The reason I'm zeroing in on filler latch assembly is - you hear noise in that area. There is nothing there that should be making noise. The rear body module has no relays that would click - it's solid-state switches - they make no noise.  Something in that area is making noise, and the only thing I can think would do that is the filler latch assembly.


It's located under the rubber and plastic surround around the gas filler and appears accessible without major disassembly. It may require that the hinge-assembly and surround be replaced if it's removed from the car. The manual isn't entirely clear on that.


I just went and took a look at how it works. It's a spring loaded piston that rotates 1/4 turn between in and out. It engages and locks itself to the actual gas filler door as it retracts. When fully retracted some sort of catch keeps it that way, holding the gas filler door closed. When you open it - that catch releases, it pushes the gas door open about 1/2" and releases itself from the door.  The lock on it must be when it's locked it doesn't release from the catch that keeps it retracted.  Typical German complexity for what should be a simple device.. You might leave the door open and see how it works by pushing it with the locks unlocked, and then again with the car locked. If it's making the noise you hear - you might have found the problem.


One other scary thought - has your vehicle ever suffered from the flooded footwell syndrome that all Cayennes are prone to? Given how the wiring for that device must run from that corner of the vehicle to the diagonal opposite front corner - chances are the wiring runs in the bundles that can be damaged if the footwells flood for any period of time.  They're fixable - and could account for the problems the Durametric is having with communications.






Edited by deilenberger
  • Upvote 1

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Wow, Don, thank you - this is going above and beyond.  


I have played with the gas cap quite a lot.  I've done things like, locked the car while leaning on the cap, locked while pulling outwards on the cap.  Made no difference, but your experiments make me want to persevere with it. I take your point about that being the only "clicking thing" in that area.


I know what you mean about the complexity of the lock - also strange the way you can do the push the cap while locked, then unlock and the cap pops out without touching it. 


Right now the problem is...it's not doing it.  Not all day today and not this evening when I just went outside to play with it.  I haven't changed anything, haven't filled with gas etc - just opened closed all doors and tailgate. However, long experience tells me that anything that is 'fixed' but you don't know how/why...will come back to bite you, and just at the worst moment. 


I'd never heard of the flooded-footwell problem, I'll do a search - no sign of damage/residue when I swapped out the battery at the weekend, but then I was hefting lead+acid and not really looking for that.  The interior of the battery compartment was spotless though cos I looked for acid-spill residue etc. 


Thanks again and I'll keep you posted, maybe even take you up on that drive to NJ - it's been a while. 






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The footwell floods are quite common. They don't come up to the level of the battery compartment. There is about 1.5" of open-cell molded foam under the front carpet. Under that foam are big bundles of wires going hither and tither - that have splices in them. The foam gets soaked, meaning the bundles of wire are basically underwater, and the water creeps past the rather poorly sealed splices, and combined with electricity - cause electrolysis - basically converting the splices into a form of copper-dioxide. Which isn't a good thing.


When they go wonky - there are all sorts of odd behavior that's been observed - especially if one of the bad splices happens to be in a computer data line.


I'll see if I can find a thread to read about it.. it is an ALL Cayenne sort of thing. None of them are immune to it - from the first 955 up to the last 958.


See: https://rennlist.com/forums/porsche-cayenne-forum/1002135-if-you-re-thinking-of-buying-a-955-957-2003-2010-read-this-first.html

Specifically the section entitled: 955 & 957 - Cabin Floor Flooding:

Also see: https://rennlist.com/forums/porsche-cayenne-forum/987845-help-my-floorboards-are-flooded.html



Almost everything described in these threads (on the 955/957) applies equally to the 958.  Makes a good case for parking it in the garage..

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Well as I stated somewhere above "anything that is 'fixed' but you don't know how/why...will come back to bite you" - and of course, it has now come back, only worse. Completely predictable.  


latest code reading session was very clean with the exception of this one:

BCM Rear

4639 / 121F
Warning Indicator On
Test Not Completed  blabla...
Fault Active


That code persists after any attempt to erase it with Durametric.  Googling that code gives no results whatsoever.  Is there a master decode list somewhere for all these codes? - maybe only the dealers have that. 


To repeat the symptoms, Car locks normally, 2 beeps then lights go out - then after some period between 10 and 120 seconds, the hazard flashers come one, lights at base of tailgate (inside) come on, loud clicking 2x speed of hazards from panel right of cargo space (i.e. inside of gas cap, but further rearward).  Door red LEDs go bl.blip...bl.blip instead of slower single flash.  Goes on forever, only 'cure' is to not lock the car.  I removed the little grill that's inside the base of the trunk side window and slid my new handy WiFi borescope in there - found there are about 3 "computer" boxes in there (i.e. boxes with connectors) but couldn't really read any labels apart from "7P0.907.801.C;" which is a Parking Brake control module.  Couldn't tell what was clicking, convinced myself it wasn't from the gas flap lock but further towards rear. 


Battery is new. charging voltages etc are all good.  Could be a footwell flood problem as Don suggests above. 

So am bracing myself for a dealer visit for some proper diagnostics - but wondering whether anyone has heard of such a thing. Or knows what 4639/121F means.  





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13 months after originally requesting help with this problem - I fixed it today.  

The car eventually got to the point where, when you used the remote to lock the doors, they would lock (one exception described below), then the hazard warning lights would immediately flash and do so forever, or until the battery was flat.  There was no beep from the alarm system. 


One other clue was that the left rear door failed to lock, you could always open that after locking the car.  I had a new lock actuator fitted - that cured the door not locking, but not the flashing lights. 


The guy who worked on door lock pulled codes with his box which is evidently better than my Durametric since I had never seen these:

C13212 Communication with alarm siren (rear 2)

C13112 Rear control unit LIN Bus fault: alarm siren (rear 2)


Lots of googling with the new clue "alarm siren" and I found this thread on rennlist:  



Cayenne DIY - 958 Cayenne DIY: Replacing the alarm module - Mine went bad. When I lock it, the hazard lights get activated non-stop until I unlock the CTT. LED front and rear lights are bright enough for neighbors to complain at night. Part #: 1K8951605B 1) It is not under the fuse box in the engine...



That thread is "closed" for some reason so I PM'd the guy and he confirmed that he had the same problem and replacing the siren fixed it. So I repeated his job today and mine's fixed too. The alarm siren (new part # 1K0-951-605-C - about $160 from everyone) is located underneath the wiper-motor assembly at the base of the windshield. So you have to:

1) remove wiper-arm nut caps

2) remove 16mm wiper arm nuts x3. Easier to get the 3rd one if you disconnect the hood-stay and lean the hood back onto the (well-padded) windshield

3) use a wiper-arm puller to remove the arms - i'd marked the spindles/arms so I could put them back on the right spline

4) lift up and remove the wide plastic piece that fits along windshield base

5) 5 screws (T30) hold in the wiper mechanism - all pretty obvious

6) unclip the big wiring harnesses and hold to one side as you lift wiper system out - unplug big connector to it as you go - siren is now revealed

7) he removed the siren-bracket from the bulkhead instead of siren from bracket - I did the same, connector is awkward

- then new one goes in and re-assemble everything.  Test the wipers and test the lock button.  All good. 


The part is plastic alarm siren made by Cobra in Italy - seems like a pretty crappy piece. 


Thanks for all the help above, cheers, 




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By the way - re-reading above - huge thanks to Don and I especially endorse his suggestion that I try a different diag, tool to Durametric - I should have asked the Porsche mech what he used but maybe it was the iCarScan that Don proposes.  Anyway, I would have nailed this 10 months ago with a better tool. 



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Richard - most of the Cayenne- DIY posts on Rennlist are locked for comments since I didn't want them becoming chit-chatty, plus the original posts they originated from are still in the original forums and are open to commentary. The idea being to keep the DIY to strictly DIY..

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Sorry to dig up an old thread -- but my 2013 Cayenne S is exhibiting this exact same behavior and I also saw a "Communication with alarm siren" fault when I plugged in my iCarScan OBDII tool.  However, mine actually makes an audible "chirp-chirp" when I lock the door -- but all the symptoms you pointed out in your comments are identical to what I'm exhibiting.  Did yours also "chirp" when you locked the door when you were experiencing this problem?  I'm just wondering if I have the exact same problem as you and that of the person on the rennlist DIY thread (that's been closed) since I can actually hear chirps?




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Mine used to chirp maybe once, and only sometimes do the hazard-flash.  Then it got worse and stopped chirping, hazards flashed immediately and all the time. The guy on the closed thread replied to me privately and said "Replacing the Siren with a new one (I think the new one part# ended in D) fixed the problem"


Having now held a bad alarm-siren in my hand and felt the (lack of) quality, I'd definitely make that the first thing I'd change. It's in a vulnerable place (underneath water streaming down off windshield) and has its connector facing up into the flow.


It took about 90 minutes to do it - awkward place so I ended up flat on my stomach lying across the engine - let me know if you need any help. You need a windshield wiper arm puller. Mark up the wiper's splines before removal so you can re-align them afterwards.



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1 hour ago, Loren said:

If you have two alarm chirps when locking then you have an alarm fault. You should also have alarm fault codes - please post the codes.

Loren, two alarm chirps is correct when the car locks. 


see page 20 of the 2011-2012 Cayenne manual - extract below. 



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13 minutes ago, Loren said:

Alarm chirps and Locking chirps sound very different. Which is yours? a normal locking sound?


Okay then I don't understand. The locking chirps are made by the alarm siren. I'm talking about the locking chirps - I think Johnny is too.  

[sorry - I wrote "alarm chirps" - now edited]

Edited by doublegarage
mis-stated something

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