knfeparty

If anyone knows anything about "pressure sensor short to b+", which is code 000257, that would be much appreciated. I cannot find any mention of an air suspension pressure sensor in the PET catalog.

knfeparty

information book has a diagram showing the pressure sensor in the valve block (which makes sense).

Looks like I'll be replacing my valve block...

knfeparty

I haven't worked on the cayenne much since the last post; replacing the front right strut seems to have sealed the system up. Repairing the wire on my "new" compressor (that was delivered with a broken wire) also seems to have solved all of those issues with the changeover valve fault. The car isn't doing anything crazy and is staying pretty level but I'm also not using anything other than Low or Normal.

I have the valve block in hand and will swap it out once I can arrange for another Nitrogen fill.

I'm not sure how critical a PIWIS is for the fill. There is a "fill mode" for PIWIS but the accumulator fill fitting is just a schrader valve.

stiles_s

We (with air susp) will all benefit from your knowledge at some point. Thanks for being a pioneer!

knfeparty

I try not to be a pioneer in my stuff breaking, but this isn't the first time it's happened to me.

deilenberger

"Experience often teaches things you're rather not know.." (A friend..)

knfeparty

garrett376

What faults are listed with the PIWIS when this happens?

knfeparty

000284 control position not adjustable, vehicle too high or too low

deilenberger

I imagine a PIWIS is capable of reading the values from each corner's height sensor.. do they look rational?

knfeparty

The tech did this and ran through the calibration procedure with the special things you attach on the hubs for measurement. He ran component tests on the sensors and they passed every time as well.

RAudi Driver

Bumping the thread to keep it alive and easily accessible

Served

My 2011 CTT just had an air suspension failure as well. Went to put it in high mode to exercise the system and the compressor wouldn't shut off afterwards. Ran for about 20 minutes straight, then died. Compressor will not kick on at all now, and dash says "Not Possible" when pressing the level control switch and of course Chassis Failure.

Codes I got were:
000257 pressure sensor short to b+
000284 control position not adjustable, vehicle too high or too low

40a fuse for the compressor tests good with a test light. Also did a few bench tests on the relay - relay clicks when energized and resistance check with multimeter read about 70 ohms(in spec). Have not load tested(with test light) the relay yet when energized which is the last check I could do on it. All 4 corners sitting low now 2 days after the failure, front right a little lower than the rest. System pressure reads 3.4 bar on my scan tool so definitely a leak somewhere(10 bar is minimum system pressure per alldata) There were symptoms previously with the car. No sagging, drooping, warning lights or compressor coming on often that I noticed. A very sudden failure.

Seems like there are alot of 2011 Air Suspension failures on here. Interestingly, on alldata under Suspension Control Module >> Testing and Inspection I found this section which indicates that there was a defective batch of compressors installed on certain 2011 models, so for some the leak may be coming from the compressor itself. Mine falls in the date range listed.

-------------------------
WM 431555 Eliminating symptoms on chassis: Replacing compressor for levelling system (for I-no. 350/351) (Levelling system/PASM defective/SY0211)
General information

Symptom

Function of levelling system/PASM (also referred to below as chassis system) (for I-no. 350/351) may be defective:

• The vehicle is too low in general or at the front.
• The compressor comes on frequently.
• The system is rarely available or
• It takes a long time for a requested function of the system to finish.
• In addition, the red warning light in the instrument cluster can come on with the following message: Chassis system failure.

One or more of the following fault codes are stored in the fault memory of the levelling system/PASM control unit:

• FC 000 284 - Control position not adjustable, vehicle too high or too low
• FC 000 320 - Level control implausible or
• FC 000 328 - System air quantity too low (rapid filling active).

Cause, date of introduction and remedial action

Cause

The air suspension system may be leaking due to fine cracks in the compressor crankcase.

Date of introduction

A defective compressor may have been installed in vehicles produced in the time period from 19.04.2010 up to 10.06.2010.
...

The rest of the document is basically a flow chart for testing the compressor using PIWIS(my launch x431 scan tool seems to be able to do most of the same tests/procedures)

My car is getting towed to the dealer friday. R&Ring the compressor itself seems like a straightforward DIY, filling the system correctly and calibration in the driveway not so much.

knfeparty

knfeparty

Update: the remaining fault is still 0284. I have pretty much all the symptoms of WM 431555 posted above by Served, except that the car doesn't seem to be low or lose height. My compressor was already replaced, however I bought it from RMT as a "new continental compressor" but of course already discovered that they attempted (and failed) to solder a new connector onto it. I now wonder how "new" it truly is. Likewise the air valves I bought from them are the wrong threads and don't fit the struts.