METHOD FOR OPERATING AN INTERNAL COMBUSTION ENGINE WITH A TURBOCHARGER ARRANGEMENT AND CONTROL UNIT FOR AN ENGINE WITH A TURBOCHARGER ARRANGEMENT

Methods are provided for controlling an engine. One method may include adjusting airflow to a turbocharger arrangement with a turbine bypass valve bypassing a first turbine from a high-pressure turbocharger and a wastegate bypassing a second turbine from a low-pressure turbocharger; responsive to valve degradation, setting the turbine bypass valve fully open and the wastegate fully closed; and limiting engine torque based on a flow through a compressor of the low pressure turbocharger. In the event of valve degradation, limiting torque may reduce overspeed and surge of the low pressure turbocharger.