Sounds like a dodgy sensor to me...?
You should able to set the position of the sensor arm to give the ride hight you want. If not, the sensor in your case sounds like its not registering correctly.
Ideally set the sensor with the natural unloaded ride hight if the springs.
And I don't suppose there is any point mentioning that 65 mill drop is too low...? If you hit a bump big enough, or take off a bump, so the rear suspension tops out, the springs will fall out while your driving it!
already know its too low mate, when i boot it the center boxes smack cats eyes on overtakeing!! they are a full set of irmscher springs off another omega & should only be a 30mm drop but they sit way lower!! think they are car not estate springs...
the car was not on mv6 setup but police HD springs/S/L shocks & i had over 4" of clearance above tyres on rear & didnt move when loaded up so car, car felt on cornering like it wanted to throw its self off the road due to center gravity been so high...
so i removed the H/D rear springs that were well & truely wedged in even with the shocker off... i fitted the irmscher springs & car sat lovely & level.. then i put fuse back in & because the wishbones were flat so to speak the S/L system thort the car was very low so tryed to lift its self back to the police settings this i didnt realise at the time....
as i "thort" the car monitored front & rear ride hight... nope just the rear... but by then was too late... for the last 3weeks ive been running on frontera v6 front dampers with modifyed eyelets to make bolts fit so i had a shortened damper that would work...
but as springs were softish guessing as they were about 15years ish old (off a 95N elite) they have lost there tension...
so when loaded up rear sinks with only 2" clearance to bumpstops..... & they hit on slightest bump!
ive contacted every company i can think of but only bilstein make a shortened rear shocker for an estate.. but 7companys make sports/lowered springs but no shockers to suit?? work that out...??
so it was eibache&bilstein (B12 kit) for £618 but no adjustment thats it... 30mm all round...
Or coilovers from Ni coilovers in ireland for £400 fully adjustable from 20mm-120mm with a heavy duty rear spring for loads upto 1360kg from standard 1060kg they would normally supply...
so atmo the s/l rear shocks are an experiment before i put a hole or 2 in my mid pipes & center boxes on rather speed bumps!
the car is fine unloaded but need that bit extra lift when its loaded up with tools or 3ppl in back seat...
Hope i havent confused you too much....??
& i calnt refit the police rear springs (tryed too much tenshion) & the front is lowered & car would be worse to drive & look like a drag racing funny car
& no body has or is braking a mv6 estate for last month that i could use springs off etc