Determining an exhaust gas temperature

A method (200) for determining a temperature of an exhaust gas stream which emerges from a cooled by a cooling liquid exhaust pipe (125) of an internal combustion engine (105) in a motor vehicle, comprising the steps of: - determining (215) a heat transfer coefficient (α) between an inside and an outside of the exhaust pipe (125); - determining (220) a factor of the heat transfer coefficient (α) and a ratio of a specific heat capacity of the cooling liquid and an effective surface area of ​​the exhaust pipe (125); - determining (240) a temperature difference between the cooling liquid on the outside of the exhaust pipe (125) and the exhaust gas stream at the inlet to the inside of the exhaust pipe (125); - determining (255) a mass flow (m) of through the exhaust pipe (125) flowing the exhaust gas stream; - determining (260, 265) a drop in temperature of the exhaust stream in the exhaust pipe (125) as a product of the factor, the temperature difference and the mass flow (m); - exiting determining (270) the temperature of the exhaust gas from the tube (125) exhaust gas stream as the difference between a temperature of the in the exhaust pipe (125) entering the exhaust stream and the determined temperature drop, - wherein the heat transfer coefficient (α) of the exhaust pipe (125) based on a fluid velocity (w) of the cooling liquid is determined on the outside of the exhaust pipe (125) and the fluid velocity (w) by means of a two-dimensional interpolated map on the basis of a rotational speed (N) of the cooling liquid in the flow offsetting coolant pump (135) and an opening degree (Φ) is determined of a coolant valve (140) in the flow of the cooling liquid.