W12 sagging rear end

[bjam]

Hello all,

The rear suspension on my w12 has been totally deflated for a few months,havnt had chance to look into it up until now.The front bags are holding air fine,ive not heard the air pump work at all since this issue

Put it on a friends vcds yesterday and we got this code

Address 34:level control labels

VCID: 280AF1E65EF89BB7F65-807C1 Fault Found:00668 - Supply Voltage Terminal 30 009 - Open or Short to Ground Freeze Frame: Fault Status: 11101001 Fault Priority: 2 Fault Frequency: 1 Reset counter: 159 Mileage: 264170 km Time Indication: 0 Date: 2021.06.27 Time: 19:13:49

The "supply voltage terminal 30" is also coming up in a couple of other items on the list

Anyone have a clue as to where I should start looking?