Buick Park Avenue Rear Air SHocks

I have a 03 Park Avenue and recently replaced the air shocks on the rear (leaking). My problem is the car thinks they should be inflated to the max all the time. I have replaced the sensor with a used sensor ( I have not been able to find an aftermareket sensor or a new one). Any ideas on how to get it to level out?
Miles now 145,000.

Have you tried adjusting the sensor mounting point to get to achieve the proper pressure for a level ride? Does it have a little lever that moves up and down with axle position?

+1 to @Caddyman. The link that connects the sensor to the axle is easy to knock off. If the link is on, are you sure you have the right model sensor? You can still buy these from GM fairly cheap. See the link below.

http://parts.nalleygmc.com/products/Buick/2003/Park-AvenueULTRA/LINK-Air-Suspension-Height-Sensor/3013640/25604758.html

Plus 2 to Caddy. Check to make sure that arm is connected. Mine got knocked off from a clump of snow and the car just dragged in the back or the rear end was way up in the air. Worse comes to worst, you can disconnect the whole thing and add a manual kit to pump them up with an air hose to where you want them. That’s what I finally did when the sensor went and wasn’t going to pay the $350 for a new one. A $5 kit from NAPA with the shrader valve and plastic air lines.