that_tg

Forgot to come back here with the update.
It was the release valve on the pump that would not let the car down. Replaced the pump everything is working great. Thank you all for your help!

dvs_dave

Glad we were able to help you fix it and get you pointed in the right direction with regards where to look.

audid3lover

In regards to you replacing your valve block, did you have to follow special steps to replace it? I am replacing my valve block but not sure if i should let the air leak out while i move the lines to the new block. Don't want to damage my car replacing it.

that_tg

Yes, make sure the car does not bottom out on something. You can undo all the lines letting the air out but the car will drop so plan for that.

AEightSilver

I have the exact same issue and same single 014400 upper limit code as the OP with some subtle differences:

• I can control the front using VCDS, raise and lower using the bleed/fill tests.
• I have checked all level sensors and none are visibly broken. No other codes to indicate issues with the level sensors.
• Suspension calibration will trigger lowering of the front. I would pump them up first to be sure before the calibration. You can hear the air bleed off when lowering.
• Accumulator will pressurise at around 10-11 bar so I think my pump is good.
• The rear will not bleed at all and is stuck high. Like the OP I was able to fill it a bit. When trying to bleed the rear, the actual pressure shows at only 1.63 bar to start
• The rear will not move during calibration
• The system is not leaking and there is no settling of any corners when leaving overnight.

So while the OP changed out the pump, I am not convinced the issue lies here in my case because I can control the front up and down just fine it seems but not the rear. Since the accumulator fills to 10-11ish bar, I think that rules out a week compressor. I am suspecting the solenoid block or the controller module itself as since the front raises/lowers, the pump exhaust solenoids must be working fine. I can hear the clicks in the solenoid block for each corner when doing each step of the suspension calibration but only the front actually moves.

I will try and manually release the pressure from the lines in the rear and try the tests again.

Does anyone think that my line of reasoning is invalid? Is there anything I am missing here?

ltooz_a6_a8_q7

It looks like the VCDS figured out everything for you already. Do you know why the OP changed the pump? What does "over inflated" means with the compressor? If you can answer these questions, you may find the problem or not
Cheers,
Louis

AEightSilver

I think the OP changed the pump because the whole car was riding high and there was no pressure release from any of the 4 struts and this was caused by bad exhaust valves on the pump. It affected the whole car so that made sense whereas in my case its only one set of struts affected (rear).

AEightSilver

Update: The more testing I did the more I believed the issue to be the pump itself, the exhaust relief valve, so I ended up changing the pump out myself. I used the jacking points plus put the jack stand on the subframe 'bump' as shown on several posts here.

The pump I got was from Rockauto Model: SKP SKAS058 for $280 CAD plus shipping/taxes. Installation wasn't to bad either: fog light and cover off as well as part of the front belly pan and fender liner and then basically its 3x 10mm bolts/nuts and the 3x connectors. I had a bit of concern over the air hose connection but this one doesn't hold pressure to leak. When the hose is removed the car suspension doesn't drop. Reinstalling the hose was a bit tricky and I removed the air nut completely from the new compressor following the removal logic. Some Google information said I only needed to jam it in there and tighten it down without removing but it seems working well even with the little locking collet being installed with pliers. Total job took me around 4h.

At this point there are no codes anymore. I was able to do the suspension calibration without issue and the car measurements are what should be expected at stock height. I may lower it a bit with coding, we will see. I'll run it like this for a bit and see if the problem has truly gone away.

I plan to do some bleed/charge testing on the front/rear/accumulator to see if those test results are any different from the original ones and will look to see how much of a rebuild I can do with the original wabco pump as far as the exhaust valves go.

AEightSilver

Forgot to mention that the under dash relay is being changed also for good measure.

AEightSilver

So the issue is still there. I went on a long 200k trip today and about 20k in the amber suspension light came. I haven't scanned it yet but I'm guessing its the same single 01400 upper level reached code as before. If I stop and start the car, the dash light clears until I drive for a bit and it comes back. Disappointed that the compressor wasn't the issue. I guess I'll start on the level sensors next. Does anyone have the part numbers handy?