D3 Code U0132 and Sagging rear end

[shining]

Hi All,

UPDATE:
I have found a small leak in the compressor. It is the hose from the dryer to the exhaust valve. When I repair this will the U0132 code disappear as well?

Original Post

I have been getting suspension errors over the last couple of weeks. Primarily "normal height only". Today I have had a chance to collect the symptoms. Unfortunately no obvious problems have jumped out at me and my searches give me too many options to know where to start.

Symptoms;
Fault code U0132 after about 5 to 15 minutes of driving. Lost comms.
Vehicle ends up sinking to the bump stops after a couple of hours parked.
On start up (with drivers door open) on the bump stops, the compressor runs for a couple of minutes and then stops with the release from the pressure release valve on compressor and does not run again.
When I shut the door she rises to standard height the compressor runs and continues to cycle, with only a few seconds between each cycle.
Same occurs on off-road height. The front rises slower than the rear.
On switching off (with the door closed) the rear of the vehicle drops.

There are no obvious air leaks.
I still have the original Hitachi compressor fitted.

Questions;
Is this likely to be one problem (eg wiring to the rear valve block) or multiple problems (plus an air leak). The boots over the bottom of the rear air springs are shot.
Is it possible that that the fault is with the reservoir valve block. Is the a pressure relief valve on the reservoir block that might be losing air?

Thanks in advance.