Replaced all 4 bags not too long ago. Decided to go ahead and replace the valve block too under preventative maintenance. A couple days later, I got "chassis system fault" with the yellow shock absorber icon. It popped up, stayed there for about 5 minutes and then vanished. Came back a couple days later. Disappeared shortly after it appeared. Eventually, these errors started coming more frequently and landed on the "more on than off" state. Couldn't engage sport mode, couldn't get the suspension out of 'comfort'. Compressor sounded like it was running right after start-up, then it would shut down and the error would pop up so my first suspect was the compressor. Then the light would go out and everything would work 100%. Not the compressor. Replaced the relay. No change. Pulled the codes and looked at the live data and everything looked good, but I saw "pressure sensor short to ground" stored in the memory. One of the pressure sensors I know of is in the valve block, which I'd just replaced. RockAuto warrantied the (Arnott) block. Put it in, no errors and the system works great.

Really easy job to replace the block. It took me about 30 minutes total. Some tricks regarding letting all the air out of the system and then getting it re-inflated, but it's not brain surgery.

Anyway, for me, "chassis system fault" was the valve block.