Disclosed is a method for diagnosing the function of a level control system (1) of a motor vehicle, comprising at least one valve (2a, 2b, 14, 26) and a control unit (10). An exchange of pressure medium from one side of the valve to the other side of the valve is possible when the valve is open, and an exchange of pressure medium is prevented when the valve is closed. The valve carries out a change of state, a variable (4, I) influencing the valve output is measured during the change of state, the measured variable influencing the output of the valve is compared with a reference curve, a family of characteristics or a limit value in the control unit (10), and based on the comparison in the control unit (10) it can be established if the valve has carried out the change of state.