Method and device for operating an internal combustion engine

An internal combustion engine comprising:

• at least one cylinder,
• one exhaust gas tract,
• a exhaust gas sensor comprising a heating device arranged in the exhaust gas tract,
• a control device coupled with said gas sensor for determining an exhaust gas temperature of an exhaust gas flowing in the exhaust gas tract as a function of the heating power supplied to the heating device,
• wherein the control device is operable to determine an estimated value of the exhaust gas temperature as a function of a physical model of the combustion of the air/fuel mixture and of the exhaust gas tract as a function of at least one operating variable of the internal combustion engine, but independent of the heating power supplied to the heating device, and
• wherein the control device adapts model parameters of the physical model as a function of a deviation of the estimated value and of the exhaust gas temperature determined by means of the supplied heating power.