Deanomite

New 11 CS owner here. 54K miles and have had it about one month. Love everything about it, but now have problems.

Vehicle has PASM and air suspension ride height adjustment, however, the ride height is stuck in Low Level. Car has been fine up until now. It will go down to loading level and will go back up to low level, but will not go up to normal or any higher levels. The display says "Not Possible" and the arrows on the dial keep flashing as if its attempting to raise. There are no other lights or messages other than "not possible".

I have reset (held the adjustment button up 10 seconds to disable controls) several times. I have driven it around but it still stuck. It was not on a lift or on jack stands.

I've noticed the front passenger level has been about half an inch lower than the driver's side since I bought it.

I'm pretty green when it comes to the Cayenne, so bare with me. I've done plenty of searching and googling, so here I am now.

I experienced this one time before on another 11 CS that i test drove. It was stuck in normal mode. It would go down to loading level and back up to normal, but anything higher said "not possible". The dealer said it needed a new transfer case. I did not buy it.

CarGuyNVA

Just guessing here, but your vehicle may need a new air suspension pump/compressor (whatever it's called). My CTT needed a replacement around 35-40k miles, covered by warranty. These are typically pretty bullet-proof AFAIK, but as with any part, sometimes they fail early.

Deanomite

So this morning it was on loading level, which was odd because I did not set it on there last night. Same issues on startup. I drove it for awhile and then it decided to work. It works all the way up and down now. Seems like it takes awhile? longer than usual but it works.

perhaps tires are low and when they heated up on driving the car was able to level itself?

I have access to a PIWIS (sp), maybe it threw a fault code?

So far its working, but odd behaviour.

deilenberger

I can promise you - low tires have nothing to do with this..

Get it on the PIWIS - that should tell the story, there are undoubtedly some codes stored in the air suspension module.

AGARubberDuck

I'd guess you have a valve letting air out of the system. Mine is doing it too but the pump can generally keep up. Either that, or one of the height sensors is getting flaky telling the system to let air out, then pump it back up.
As far as the 'not possible' message, it seems the indicator on the selector switch shows where it is, and where it is going, but not necessarily what has been selected. I was driving down the interstate in what I thought was the low setting (according to the indicator), and wanted to bring it up to normal for ride comfort but was told not possible. Later I looked and sure enough it had brought itself up to normal.
Also on that rather long trip, I'd periodically get "chassis fault" in red taking up the whole MF guage screen. That error would come and go, but seemed to be related to the system being unable to fulfill my request to change the ride height.
I'll get it checked out at the stealership next week and report back if you haven't figured it out by then. (48k miles on my 11CTT)

deilenberger

The 958 "air" suspension system is actually a nitrogen suspension system, and unless there is a broken component causing a leak - nothing is "vented" to atmosphere.

I suspect lack of use may be part of the problem. If you don't exercise it once in a while the valves may get sticky causing them to not open. Cycling it up/down a few times may be all that's needed to free them up.

AGARubberDuck

Hmm.. Learn something every day. Perhaps it isn't venting to atmosphere, but certainly makes an audible "Pshhhh!" noise and deflates with Gusto, quickly followed by re-inflating with a much quieter "shoooo"

deilenberger

There is a reservoir tank (aka "Pressure accumulator"), located about under the driver left leg..




#5 = Pressure accumulator

From the manual:
I suspect the sealed system was designed to reduce failures caused by "wet" air being pumped into the open-system used on the 955/957 vehicles. As anyone with a compressor knows - compressing air drives the moisture in it out of suspension, and droplets of water will form. Having them in the valve bodies probably isn't good for longevity. Having the system sealed and filled with nitrogen (naturally dry) should lead to improved reliability.

Deanomite

Thanks for the input. The vehicle was working fine for about a week just fine and working in all levels. I do use the ride height setting regularly to keep the system "exercised".

Last night I put the vehicle in loading position, left it overnight, and this morning the same problem came back, it would go to low level (one up) but not to normal or higher. The button will keep flashing and I hear the compressor making noise on the passenger side of the car trying to go up forever. I click it down once to cancel it so it does not overwork itself. In general the vehicle seems to take a longer time going to and up from the loading level. deilenberger, You might be on to something with your pressure accumulator might theory.

I'm putting it on a lift this week to put on my straight pipes. I will disable the system by pushing the button forward to deactivate the leveling. However it is stuck in low mode. The manual says to put it in normal mode first, then disbable it. Do you think there will be any issue going on a hydraulic lift with the car in low mode, but with the system disabled?

Deanomite

It has since allowed me to go to normal mode, and is now working fully again. So it can operate functionally, something just does not want it to at times.

I also put the straight pipes on from Fabspeed - it's not bad sounding but I don't love it, but not as deep as I was expecting.
Will keep you posted once I can get the PIWIS and further evaluation done.

Deanomite

So the problem is intermittent at best. Got it on the PIWIS, and it started working fully. Now its back to not possible. Or it takes forever to reach the level. I'm guessing the compressor is going out and unable to fill enough air or perhaps the front right strut is bad since it sits about 1/2" inch lower than the driver's side.

From the PIWIS. Not sure if that is related to the air suspension or not:

fault memory / fault code: P1572: Control unit run-on not ended correctly (invalid signal)

Also a few days later a message popped up that said "Chassis system failure". I turned the car off and it has not come back. I think it came up because I shut the car off before while it was still leveling, before it had reached the level.

The PIWIS died while we were diagnosing it, so need to get it back on there to do some more investigation still.

AGARubberDuck

My dealer stated the front right air spring was leaking internally causing it to constantly (although somewhat slowly) lose pressure and pump up again. I'm not quite buying it yet as I've watched it somehow choose to pump that corner up high, let it out fast, and then pump up again to the level selected. Many times it holds its air just fine, over night even. In my mind, this seems more like an electrical signal issue - perhaps the level sensor for that strut is going bad. I'm going to try that first before letting the dealer replace a likely-good $3200 strut assembly.

FYI, the Durametric doesn't give enough information outside of error codes related to the air suspension to be useful. I haven't found a place to read the level sensor values as I could on my 04.

deilenberger

I believe iCarScan can read those values. I'll be hooking up to it later - I'll try to remember to take a look.

UPDATE: took a looksee. Can't read the actual height measurement, but can read the "deviation" between expected height and measured height - in MM. I don't know how accurate this reading is since in the "low" level it seemed to think that two of the corners - diagonal corners - had 253mm (~10") deviation. You can monitor the pressure in the system, and in the individual airbags - so if there is a leak - that would be possible to observe. You also can monitor the compressor relay state (ie - compressor on/off). And you can watch the air-valves switch on/off - but using the up/down control always gives a value of "up" to the air-valves (even if at top level and I selected a lower level.) My system works fine - despite the 253mm "deviation" values (and if two diagonal corners were 10" higher than the other corners - the car would look very odd..)

So - perhaps more useful than the Durametric, but I'm not taking any of the real time values iCarScan reads as gospel.

The earlier version of the Porsche software (which I may still have on my tablet) - did let you read actual sensor values (I remember looking at it) and I believe (at least remember seeing it) allowed you to "calibrate" the sensors (which could possibly be used to lower the vehicle, as you can with the Durametric and the 955/957 system.)

AGARubberDuck

Alright Don, you've got me sold on the iCarScan. I'm not terribly worried about seeing specific numbers, but being able to view fluctuations in real time will be helpful, especially the level sensor value and spring pressure.

stiles_s

Is the $3200 an actual quote from the dealer to replace one air strut? Holy hell. I'm selling mine before it's out of warranty