Yes the standard exhaust on the C2S has 2 flap-controlled bypass pipes (the same change over valve is used there).
They open when the engine speed is above 3,300 rpm or above a certain air mass level.

 

Thx -- that is helpful. I guess I am stuck open if louder at lower revs, too.

Other than exhaust ones, the symposer is the only other obvious sound-changing one, I would think?

 

There is an intake tuning flap on the C2S (...actuated by our best friend the change over valve), but I doubt that the position of this flap results in any noticeable sound change.

Most likely one of you exhaust valves that died. Maybe others too, but it will not be as noticeable and I do not think it throws a CEL. Better ask your dealership to check the other valves too. It is warranty work, they should like it anyhow.

 

My 991 C4S Build date March 2013 developed the PSE stuck in loud mode fault.

The dealer diagnosed as a faulty change over valve and have replaced that one. The faulty part is Rev.B and they replaced with Rev.C. As per others they refused to replace all the other Rev.Bs until they develop a fault.

My concerns are:
1. Why were they still using the known to be unreliable Rev.B when they had already issued a recall for 2012 cars?
2. It is very worrying to wait for the change over valves to fail. Who knows when they will happen and it may be detrimental to the car or happen after the warranty runs out.
3. Does anyone have information to confirm that the Rev.C is reliable?
4. Is there any way to get Porsche to replace all the Rev.Bs pre-emptively?

 

There is also a campaign for vacuum hose for exhaust, which I assume has to do with the same mechanism?

 

Wow, did you get a Fault Code on the Instrument Cluster for your PSE Change Over Valve?

When mine failed there was no visible fault code
Also Porsche of San Diego tried to play games with me stating that they would not even attempt to diagnose it, if I did not put my Sound Symposer tube back on.
As if that has anything to do with it.

Ultimately they fixed it, but only after a 3rd trip to them.
With dealers like this, I don't see how anyone can get them to replace Change Over Valves pre-emtively.

I am planning to just change as many out myself as I can get to.
It seems they fail without giving any visible fault code (at least in my experience).

 

No fault code on my dash. Don't think there was a fault code on the PIWIS either. I can hear that my PSE was stuck in loud mode and that the PSE button had no effect on the exhaust. The tech needed to use the PIWIS to manually switch on and off the valve and used his hands to feel for a click (absent) to confirm that it was faulty.

I was very diasppointed to know that even being built in March 2013 mine still had the Rev.B.

To replace the valves is it simple matter of buying the Rev.C, and unplugging the Rev.B and plug the new one in? No fluid leaks or wires to attach?

May be some one can do a nice DIY on these valve raplacements!

 

Very simple to replace. These are simple vacuum lines, nothing can leak and there is no wiring (other that power wire going to the valve). The 2 or 3 valves that are close to the intake are easy to access after you have removed the engine cover and the upper part of the intake, but the others are a PITA.

 

Update to my previous post. When they replaced my PSE valve they were supposed to have checked that all the other valves are functioning normally.

Well a few weeks later I have now lost heating to the car, meaning at least a 2nd valve has failed. They will be replacing this soon and check the other valves again. However still insisting that there is no pre-emptive replacement until they fail.

My C4S is March 2013 Build.

 

This is an extremely poor decision from Porsche (comes from HQ. They would not reimburse your dealership if they agreed to pre-emptively replace the valves)

 

FYI - the latest Change Over Valve is:
7PP-906-283-F

They were not available, as of last month, but they might be now.
I will check back with Sunset, to see if I can now order some, to do my own pre-emptive replacment.

 

Absolutely DISGRACEFUL that owners have to resort to taking matters into their own hands because this company simply refuses to take ownership of KNOWN defective part.

 

Anyone had had tuning flap and/or air cleaner box flap valve(s) fail. Did it result in a different sounding car?

My S has developed a droning around 2000-2500 rpm, that is rather annoying. It was intermittent at first, but is now permanent.

(It is not sound symposer related -- tested that by disconnecting tube to make sure. Stock exhaust is loud on startup, but quiets down as per usual, so think those valves are working.)

Had it in for check at dealer -- but came back with the dreaded "sounds normal to us" (it does not).

Thx guys.

 

After driving my 2013 CPO C4S (13,000 miles) for only four days it displayed the cooling system error. It has now been in the shop for almost two weeks. Apparently there was a campaign to replace the original change over valves in certain 991's due to weather seal leaks, and while my car did have that done, the dealer believed that the replacement valves were failing. The dealer subsequently replaced them all with the most up to date valves (ending in F) as well as the PDK and "neutral" valves. Despite this the error still appears after driving the car. They have tested each and every valve and the thermometer and are convinced that they are all working properly and that the error is a software issue. They are waiting to hear from the Porsche help desk with regards to working out the software issue in my care. Does anyone have any advice? Thanks in advance.

 

I know this is just a guess, and likely something the service team would pick-up on, but unrelated to the actual C-O solenoids the cooling system error could appear due to one of the vacuum hoses on the exhaust coming off. My SA told me that this was a "common" issue (not saying frequent, but that they'd seen this before.)

In my case, I had the Cooling System Error warnings begin appearing earlier this summer when the vacuum hose disconnected during a long drive. I noticed a deeper droning exhaust note, especially when downshifting at lower RPMs. Sounded like PSE all the time, rather than quiet and non-quiet modes.

Hope that helps....