Method for combustion engine pollution control, the engine outputting exhaust gases qualities of which relates to lambda value in engine operation, the method comprising - measuring the temperature of the exhaust gases from the engine, - controlling the temperature of the exhaust gases from the engine, - measuring NO x value of the exhaust gases from the engine, - controlling the lambda value in the engine operation in response to the measured NO x value of the exhaust gases as follows: - in case where the measured NO x value is over the reference value a signal to decrease the NO x emissions by way of increasing the lambda value through a waste-gate control device is outputted by a NO x control, and - an ignition timing offset signal for retarding ignition timing is outputted to an ignition timing control function by the NO x control, if the waste-gate control device is unable to lower the NO x value to a targeted NO x level, - average exhaust gas temperature reference, the negated measured average exhaust gas temperature, and a lambda control value from the step of controlling the lambda value, which lambda control value is based on the difference between the measured NO x value and the reference NO x value, are fed to a summarizer and summarized by the summarizer, and the summarizing result from the summarizer is fed to an average exhaust gas temperature control function, and control signals are delivered by the average exhaust gas temperature control function to the waste gate control device in response to the summarizing result from the summarizer. - measuring the temperature of the exhaust gases from the engine, - controlling the temperature of the exhaust gases from the engine, - measuring NO x value of the exhaust gases from the engine, - controlling the lambda value in the engine operation in response to the measured NO x value of the exhaust gases as follows: - in case where the measured NO x value is over the reference value a signal to decrease the NO x emissions by way of increasing the lambda value through a waste-gate control device is outputted by a NO x control, and - an ignition timing offset signal for retarding ignition timing is outputted to an ignition timing control function by the NO x control, if the waste-gate control device is unable to lower the NO x value to a targeted NO x level, - average exhaust gas temperature reference, the negated measured average exhaust gas temperature, and a lambda control value from the step of controlling the lambda value, which lambda control value is based on the difference between the measured NO x value and the reference NO x value, are fed to a summarizer and summarized by the summarizer, and the summarizing result from the summarizer is fed to an average exhaust gas temperature control function, and control signals are delivered by the average exhaust gas temperature control function to the waste gate control device in response to the summarizing result from the summarizer. - in case where the measured NO x value is over the reference value a signal to decrease the NO x emissions by way of increasing the lambda value through a waste-gate control device is outputted by a NO x control, and - an ignition timing offset signal for retarding ignition timing is outputted to an ignition timing control function by the NO x control, if the waste-gate control device is unable to lower the NO x value to a targeted NO x level, - average exhaust gas temperature reference, the negated measured average exhaust gas temperature, and a lambda control value from the step of controlling the lambda value, which lambda control value is based on the difference between the measured NO x value and the reference NO x value, are fed to a summarizer and summarized by the summarizer, and the summarizing result from the summarizer is fed to an average exhaust gas temperature control function, and control signals are delivered by the average exhaust gas temperature control function to the waste gate control device in response to the summarizing result from the summarizer.