the rear suspension sinks after 20 mins but comes back up again when a door is opened ( pump runs when door is opened as normal ) once it's driving rear hight is normal

i jonsson, April 2013

You don't say what kind of car it is but on certain cars and trucks there is a sensor that tells the air ride system how fast the car is going or standing still and lowers it closer to the road changing ride performance. On trucks with towing packages the sensor picks up the highth of the truck when it's carying a load or is pulling a trailer and pumps up the air ride back up to level the load. This is caused by a faulty sensor or sensor wire conections or a air pump relay malfuntion.

thomasedwin, April 2013