I do not mean to light a fire for nothing, but I got increasingly concerned by what seems to be a lingering issue with change over valves in the 991.

Here's a picture of the part in question (the part number is 7PP906283B, now replaced by 7PP906283C):



Based on a quick research on the internet, it looks like Porsche was aware of the issue for early 2012 builds and that launched a recall campaign (WC-43) intended at replacing 8 of these valves.

In my case, my sport exhaust stopped functioning and 3 out of the 4 change over valves I have checked were bad (I did not check the others).

There are also various threads about 991's built at different times that have had heating/cooling system issued. Again, the same part was the culprit.

I find it intriguing that it has been going on for so long and that Porsche has apparently not resolved the issue.
The first concern I have is that you may not always detect that something is wrong: it is only when my sport exhaust stopped working properly that I discovered it, but the valves controlling the symposer and the intake flap were already bad. The second concern is that I read that this part would be used in more critical components (PDK).

Change over valves (simple solenoids in fact) are a very common part and Pierburg, the manufacturer, supplies it to a lot of car makers, including for the previous 911 models. This part number is specific to the 991 and seems to be the one having an issue. They may not be sealing properly allowing moisture in, causing the valves to malfunction over time.

I am not posting this to alarm you but to keep this in mind and report if you had other issues resulting from the failure of that same part.
Having already had 3 bad solenoids, I intend to drop the car at the dealership to get it checked.

 

Thanks for the feedback.
Any other symptoms that a layman can look out for?

Apparently it doesn't throw an error code, which in Porsche World means everything is just fine..

 

Nope. Not 'mission critical' hence not monitored part. This is a very common part with a low rate of failure from what I have been told. The 991 issue is an anomaly...

 

I'm sure I speak for most if not all when I say many thanks not only for bringing this to our attention but for also keeping us updated. I have a May/June '13 build with no known issue yet...

 

I have had all of mine replaced under the campaign. In addition, one failed this winter and the result was no heat.

 

Is the new part problem free? When did they switch to using the new part? Thanks

 

I just had this part replaced yesterday, as I had lost all heat to the cabin. On the job description sheet, the "New" part number is listed as replacement, so I am not sure that the part replaced was the "old" or "new" part #. I should have asked.... My assumption is that the "C" new part replaced an "B" part that was already on my '14 C4S (build date 06/13), but now I am wondering if the "C" part failed?

I'll ask my service rep if he can elaborate. There was no mention of a campaign that is currently open -- but my rep did say they had seen this happen on a few cars in the past.

Here is a link to my previous post:

 

Great Info!
Thanks!

Those valves are all over the car.

PART NUMBER DESCRIPTION MG SG ILL. NO.
7PP906283B CHANGE-OVER VALVE 1 05 105-05 (Water Tube, for heater)
7PP906283B CHANGE-OVER VALVE 1 06 106-00 (2 Valves, Air Cleaner & Symposer)
7PP906283B CHANGE-OVER VALVE 1 06 106-05 (same as above)
7PP906283B CHANGE-OVER VALVE 1 07 107-10 (Intake Distributor)
7PP906283B CHANGE-OVER VALVE 1 07 107-15 (Engine Vacuum System, non S)
7PP906283B CHANGE-OVER VALVE 1 07 107-17 (2 Valves, Engine Vacuum System, S)
7PP906283B CHANGE-OVER VALVE 1 07 107-20 (3 Valves, Engine Vacuum System, X51)
7PP906283B CHANGE-OVER VALVE 2 02 202-10 (Exhaust Standard)
7PP906283B CHANGE-OVER VALVE 2 02 202-15 (Exhaust Sport)
7PP906283B CHANGE-OVER VALVE 3 02 302-15 (Cooler Trans Manual)
7PP906283B CHANGE-OVER VALVE 3 60 360-00 (2 Valves, Cooler Trans PDK)

With those valves controlling the Trans Cooler, I wonder if bad valves are what lead to PDK failures?

 

Change Over Valves failure - part 2 I found the following schematic about the vacuum system in the 991 Service Information book (you can buy it from Suncoast BTW):



It confirms my fear that more critical items can go wrong due to failed solenoids: i.e. shut off valves for engine coolant or ATF (= automatic transmission fluid for PDK). The Porsche document nevertheless mentions that "electric solenoid valves in the vacuum system are fully diagnosable (short circuit/open circuit); electrical faults result in an entry in the DME control unit and the PDK unit". I nevertheless did not get any alert for my failed solenoids and will definitely get the other ones checked ASAP.

 

Very interesting.

I wonder what symptoms would be displayed if 7PP906283B CHANGE-OVER VALVE 1 07 107-17 (2 Valves, Engine Vacuum System, S) were to fail?

 

Interesting stuff, Serge. I wouldn't mind getting these checked out, as well. I just hate to think that the dealer won't really bother doing a thorough check if I don't already have an obvious problem. They'd probably come back with an "all is well" answer.

 

Well, I agree, Christo- I was just at the dealer this past Monday for a valve failure on my 06/13 build '14 C4S and the part that failed was replaced without ANY mention of other valves being checked, and certainly not replaced. The Service rep even mentioned that "they've seen something 'similar' on other cars" in the past. If there was a campaign previously, then it must have expired or something and my June 13 build was not included.

I do intend on taking back to the dealer at some point -- tried talking to them today, but they were all literally out in the lot digging cars out!!!

Serge- thank you AGAIN for maintaining such a great level of detailed information on this board!

 

Amazing... I really do wonder how much of their alleged "checks" actually take place. I'm not paranoid by any means, but some horror stories really make me think twice about these things.

 

Hard to say on that one as it's not clear where the hoses go, for that item.

These are the diagrams and in most cases you can see the item being controlled.

 

More Diagrams