In an exhaust gas heat exchanger system of a combustion engine, having a bypass duct 9 and a heat exchanger duct 5 with a heat exchanger 7, a valve 10 is controlled by a method comprising the following steps: First, it is determined that heat is to be transferred from exhaust gas flowing through the exhaust system to the heat exchanger 7. Thereupon, the valve 10 is switched into a first position in which the entire exhaust gas flows through the heat exchanger duct 5. A pressure drop across the heat exchanger system is monitored either directly or indirectly. If the pressure drop reaches a predefined limit, the valve 10 is switched into an intermediate position, the intermediate position resulting in a first portion of the exhaust gas flowing through the heat exchanger duct 5 and a remaining portion flowing through the bypass duct 9, thereby reducing the pressure drop across the heat exchanger system. If the pressure drop again reaches a predefined limit, the valve 10 is switched into a second position, the second position resulting in a second portion of the exhaust gas flowing through the heat exchanger duct, the second portion being smaller than the first portion, thereby further reducing the pressure drop across the heat exchanger system.