02 yukon denali auto suspension stopped working ..anyone (preferebly mechanics or auto experts) know what could cause this & how estiate fix cost?
thx 4 reply ..if the dealer fixed it w/ new compress on parts&labor how much they lookingroughly?

Is the service suspension light ON.
If on, u need to scan the suspension module for codes.
In most cases it is a bad suspension compressor. code (C0660)
before u replace it , make sure 2 fuses r good.
FUSE 1 in the instrument panel fuse block (IGN 3 fuse 10A)
FUSE 2 in the underhood fuse block (STUD 1 fuse 40A)

the compressor is in the left rear corner of the vehicle.

You SHOULD have it scanned, for precise diagnoses.

Estimate will vary, so shop around. ( new vs. used ) compressor.

A new compressor from the dealer is expensive, l want to say around $500 but I'am not sure . labor should be around
1 hr- 1.5hrs. do not know what dealers in ur area get per hour.

l had the exact same thing priced out for some customers with an 03 Escalade ESV, and l had it priced at closer to $650 parts/labor if l remember right. That also included diagnostics. At my shop we guarantee our repairs by diagnosing the complaint from the customer, not just throwing parts at it based on someone else is diagnosis. It costs more but you know it is getting fixed.