Driving to a visitation about 140 miles away today (great day today), about 100 miles into the trip the air suspension fault warning comes on, no choice but to continue on, when I get to where I was going, I notice that the rear passenger side is real low, tire in the wheel well low. I jacked it up, to get that corner off the ground, and once I lowered it back down it was good, but within 30 min of sitting, it was clearly dropping back down.

Before buying parts for this, I want to figure out what I need. Relay maybe, is it the compressor, is it the shock. It is only doing this on the one corner. Also, is it safe to drive it back to get it into my garage? Like I said, about 140 miles, it's not rubbing or anything, just wondering if it could hurt something else.
Thanks

 

Dunno if it could hurt anything more, if it's the compressor I would expect you to get the fault shortly after startup as the usual sign of a weak compressor is it failing to lift the car to ride height within 3 minutes setting a message in the message centre. My moneys on the shock itself or the ride height sensor. If there's a message - there's an OBD code to be read, which might narrow it down. If it's the shock the only thing I can see as a problem is the compressor running more than usual to keep trying to raise that corner, but I would also expect the controller to have a duty cycle time to ensure it doesn't kill itself trying to achieve the impossible - I'd expect, but I don't know.

 

My guess is a air shock, it sounds shockingly similar to this thread here.

steve_tech hasn't been online in a while, as he's our resident 2004+ air suspension expert, but I'd think he'd agree.

Buck provides a link to a reconditioned air shock for $400, which is a ton cheaper than the dealer.

good luck!

 

ok...update...

so, I parked the car, basically sitting on the back passenger side tire and went to bed. I got up this morning to find it looking normal??? No Air suspension fault on the dash, I proceeded to drive it the 140 miles back home, with no issues at all. I don't know what to think anymore

 

My motto is "don't worry, be happy". Some things about these cars you don't want to know about. It could be you have saved yourself a large repair bill, at least for now.
By the way, was there anything different about the way you had the car parked when the left rear went down?