Extended ride height will not hold

[Kummer]

Hi all, thanks for the help in advance. 2005 SUT LX Adventure package with air ride. To recap system has worked fine until last winter. Occasionally when it is really cold the rear drops down...Suggestions ? Starting last spring extended air ride will not hold. It rises up when the button is pressed, gets to max height and drops down again. Then it goes through this process again, and keep repeating until I shut it down. I have had a left rear position sensor code flashing since I got the truck but have never had any problems until now.

Both sides drop, not just one. I have the airbags to replace since they need it anyway but dont think that is the problem since I have checked the system for leaks and did not find any.... Has anyone suffered this problem ?