Maybe something is only leaking above the pressure required to keep the front end up higher than that? Only theory I've got.

And you're right, the compressor should only run for 30-45 seconds after startup I believe. I can't find any exact numbers as to how long. It's supposed to shut itself off after a period of time to avoid burning itself out.

Would be nice if someone could explain exactly how the system works. From my understanding, the compressor pushes it to the front and rear reservoirs, from where it then pushes it to each of the bags. As my rear bags hold perfectly, even with the car quite loaded, I want to say that the compressor (despite running for a bit longer and not being very silent) shouldn't be the issue. Since my fronts are both dropping at the same rate, it looks like the issue has to be at the front reservoir, like you had. I tried to get to it this morning, but I'm not sure I can figure out anything meaningful without taking it apart, which is currently out of the question as I don't have a second car available. I am considering risking it and ordering that valve you mentioned and just praying for the best (happens quite often with this car, yet I still love it to death).

So today out of nowhere I had the suspension inactive error pop up. Hooked up INPA and got this error. Would this be the reservoir you are talking about that’s under the car or is it the one in the trunk?

Update:

Well this took a very quick turn for the worse. I reset it in INPA, went to try out the car, within minutes the error was back and now I can’t access the module in either INPA or DIS :dunno:

BMW documentation about EHC2 system.

^awesome clavurion. Downloading that, if I don't have it already in my disorganized e53 info files.

Patrik7, were you accessing the module with the truck on or off? With a charger?

It was off, with the key in position 2. I believe I read that to be the proper way to do it? But I swapped out the fuse and was able to access it again, so I think it’s blowing my fuse when it’s running. Going to the store now to buy all the relevant fuses for air suspension.

Thanks! Amazingly helpful documentation!

I decided to give it another go today with DIS and encountered the following:

After much googling I am still unsure what it’s referring to.

Air supply unit = compressor with drain valves.

Check the accumulator pressure. Then activate compressor and check how the accumulator pressure behaves.

I think I found the issue. One of the screws on my compressor in the trunk just snapped off and it doesn’t look to be in the greatest of shapes... looking at options to save it.

Well, the compressor is shot. Gets 2 bars now, as the screw broke of it loosened a bit and messed up the insides. Time to order a new one.:confused: