Knowledge of all relevant parameters affecting function and load is a precondition for optimal engineering of exhaust gas sensors. Access to those parameters by measurement is difficult and often impossible. Thus the development of a validated model to simulate operating behaviour of exhaust gas sensor was the aim of this work. Coupling of a 1D-engine simulation with a 3D-CFD simulation is done to predict convective momentum, heat and mass transfer to the sensor surface. Being results from coupled simulations, transient boundary conditions are applied to a further 1D-model to predict mass transfer inside the sensor. Signals of two exhaust gas sensors were simulated.