Method for operating a combustion machine, combustion machine and motor vehicle

A method of operating a combustion machine comprising an internal combustion engine, a fresh gas line, an exhaust gas line and a cooling system comprising an ambient heat exchanger as well as a cooling channel of the internal combustion engine, whereby a NOx storage catalytic converter and/or a particulate filter is integrated into the exhaust gas line, comprising:

• as a measure to desulfurize the NOx storage catalytic converter and/or to regenerate the particulate filter, temporarily setting a temperature of the exhaust gas flowing through the exhaust gas line to at least a minimum value required for the measure,
• lowering a temperature of a coolant flowing through the cooling system before and/or during the measure to desulfurize the NOx storage catalytic converter and/or to regenerate the particulate filter,
• wherein, during the measure to desulfurize the NOx storage catalytic converter and/or to regenerate the particulate filter, a portion of the exhaust gas flowing through the exhaust gas line is conveyed through an exhaust gas recirculation line which comprises an EGR cooler integrated into the cooling system,
• wherein the temperature of the coolant is lowered only when the portion of the exhaust gas that is being conveyed through the exhaust gas recirculation line is in a volumetric flow fraction that is above a defined limit value, wherein the defined limit value is larger than zero.