Method and device for operating an internal combustion engine with exhaust gas recirculation

Disclosed are a method and apparatus for operating an internal combustion engine (1) is proposed with exhaust gas recirculation (5), which allow a diagnosis of an exhaust gas recirculation cooler (10) during normal operation of the internal combustion engine (1). Here is monitored characteristic quantity for a function of the exhaust gas recirculation cooler (10). The for the function of the exhaust gas recirculation cooler (10) characteristic variable is determined as a function of a measured value. The for the function of the exhaust gas recirculation cooler characteristic (10) size is specified on the basis of the intact exhaust gas recirculation cooler (10). The value determined for the function of the exhaust gas recirculation cooler (10) characteristic quantity is compared with the predetermined value. In a deviation of the value determined for the function of the exhaust gas recirculation cooler (10) characteristic variable from the predetermined value a fault is detected.