The present invention relates to automatic adjustment of a position relationship between a motor vehicle's (110) chassis element (119) and at least one wheel pair (113; 114a, 114b) of the vehicle (110). A control unit (117) receives a target value (hT) and a measured value (h) expressing the position relationship between the chassis element (119) and the at least one wheel pair (113; 114a, 114b). Based thereon, the control unit (117) produces a first control signal (C1), which influences an input air flow from a pneumatic pressure source system (115; 116) to a pneumatically operated control mechanism, such that the a position relationship is varied. The pressure source system (115; 116) produces a system pressure (PS), and a pressure sensor means (111) registers a pressure parameter indicative of the system pressure (PS). Furthermore, the control unit (117) compares the measured value (h) with the target value (hT), compares the system pressure (PS) with at least one pressure limit (Pco1; Pco2 ), investigates whether one of at least two decision criteria is fulfilled. Upon fulfillment of such a criteria, the control unit (117) controls the system pressure (PS) to a predefined level by means of a second control signal (C2). The predefined level depends on which decision criterion that is fulfilled.