Why do Back shocks of my gl450 go down regularly when packed. on 2008 Mercedes-Benz GL450

Recently the back suspension of my gl450 often go down when packed overnight or for a long time.it goes up once the car is opened or the engine is started. it happens occassionally. What is likely problem and Is it safe to travel with it, about 500km.

Asked by for the 2008 Mercedes-Benz GL450
1 answer
you have an ayr system leak when loaded. this is a common issue with air ride equip veh. seek a diag and est