2009 cayenne S (US spec) with 74k miles on the clock.
Check engine light on with code P0455 (evaporative emission system leak - large leak detected). Picture attached.
I took it to a shop to do a smoke test, they found no external leaks. They tested the tank vent valve and leak detection pump and it failed twice. (Pic attached)
So i changed the leak detection pump (95560510702), found that the one installed was a Chinese brand not oem, drove the car for two days then the light came back again! Same error code.
Next step i want to change the tank vent valve (95560524101), is that the same as the purge valve? i found some DIY for an 03 -06 TT but the engine layout is different. i can't find any diagram online on where the valve location is. Any help is appreciated, thanks.

 

I'd also change the gas cap to a porsche oem one. Although I had a small evap leak, this gas cap fixed it.

 

It appears there are 2 valves in the evap system called purge valves. I believe the info from the code is supposed to indicate whether it is referring to the purge valve associated with the charcoal canister or the purge valve under the hood with the engine. My evap leak was/is under the hood and the shop recommended that I get the valve with the hoses already assembled to the valve since the hoses have crimped-on clamps rather than a type that is easily removable and re-usable. I have an illustration showing the part, with hoses and clamps separate items, so I am going to try to find the "assembly" with clamps and hoses if it is sold that way anywhere.

 

+1

Try this first. Cheaper and easier.

 

sorry i forgot to mention that i changed the gas cap...

 

Hi Scoot, below is a PET diagram to the carbon canister, there is no valve over there, i believe you are referring to the leak detection pump that in next to the carbon canister above the rear passenger wheel arch (which i already changed). this is why i got so confused as to whether the purge valve is the same as the tank vent valve and the "vapor canister purge solenoid"... for now i think they are all the same. just need to find out how to replace it.

 

The print out makes no sense. If the car fails the short test for the tank vent system or the tank leak system (these are two separate tests) it will set a fault. It doesn't fail and then NOT set fault. If the shop you took it to knows what they were doing on a Porsche (and i doubting it from the wording of the print out) and can properly do smoke test and they found no leaks, the tank vent valve (aka purge valve) makes sense to replace. It could be sticking open intermittently causing the tank leak test to fail. Another thing that would cost you nothing to check would be the output of your vacuum pump. Low supply of vacuum to the leak detection pump can cause tank leak faults. You should have over 25" in on a vacuum gauge when you test the vacuum pump output.

 

vvvv Agree vvvv

Another thing that would cost you nothing to check would be the output of your vacuum pump. Low supply of vacuum to the leak detection pump can cause tank leak faults. You should have over 25" in on a vacuum gauge when you test the vacuum pump.

I encountered this error and it was a defective vacuum pump...a cam driven pump on the 2009.

The engineer who wrote the diagnostic program is assuming that low vacuum = a leak. If the pump is defective, causing low vacuum, you will have the same error.

My defective pump measured 10" with this error, the new pump measured 20".

 

Take a look at post #50

https://www.6speedonline.com/forums/...ml#post4699724

and...

 

Gents just an update, i managed to change the purge valve last weekend but the CEL came back on again after driving for 540 miles.
I will check the pressure of the vacuum pump as advised by PTEC, but besides that i dunno what else to do... smoke test showed no leaks...

If anyone wants a perfectly used gas cap, Leak detection pump or purge valve hit me up lol

 

Gents just an update, i managed to change the purge valve last weekend but the CEL came back on again after driving for 540 miles.
I will check the pressure of the vacuum pump as advised by PTEC, but besides that i dunno what else to do... smoke test showed no leaks...

If anyone wants a perfectly used gas cap, Leak detection pump or purge valve hit me up lol

 

Same here as far as the gas gap. Take a look at my post above to see what I'm hoping got rid of mine.

 

Had the same issue with P0455 and sometimes even P0244 and after changing gas cap which wasn't it. Tech tested the purge valve and it appeared to be working fine.
So just recently had the Vacumn Pump changed.. Its a Pierburg part and not very expensive from Autohauz.
The indy had to also replace some solenoid, but didn't want to take off the manifold cover and all so, he actually rigged a new solenoid after installing the pump.
Not happy to be charged 4hours labor for this job though, as I figure it is only 3 bolts holding the pump albeit in an awfully difficult location for normal sized hands.
So far 3 days in and no codes. I was getting an error after 1 day so looks like the vacumn pump is the fix for now.

 

So where do you measure the vacuum at? Are there any easy accessible hoses to hook up to? And do you use a standard fuel pressure/ vacuum gauge like those available from HF?

 

Any automotive vacuum gauge will work. What model Cayenne...S, GTS?
I used a manual vacuum pump with a gauge...Mighty Vac.