Sounds same as mine (was) check all connections for water or corrosion if not it may be water in one of the height sensors :-(

Can you get it on diagnostics? Then post up a screen shot??

Datatek said:

There is no multiplug on the air tank

Click to expand...

That'll be why I've never found it!

Testbook did show up connector to air tank once though

Would the compressor running for 30 minutes flatten a battery though?

Any news?
I have the same problem, I did change 4 height sensors(new); new air springs and also with used drive pack (same result).

Other thinks that I noted, and can be or not important, but I "share" for free
1 had a "fight" with pc to calibrate new sensor, the eas Ecu was "reseting".
(With my cable and PC, and also with the PC/cable of my friend).
2 I noted when the RR run high, and with 4/5 people, and when we all leave the car, he gets more higher and stay there ( I think that´s not normal).
3 the other thing strange is when I change my last "original" airbag (+- week 4*/98), the RR was "only" in the bump stop of the dead airbag.
I open the RR (to get my garage door remote), close the door, and I have the valveblock "music" and she go to the 4 bump stops. Weird no?
EAS relay problem?
(the RR was not used about 4 weeks).