An engine system for a vehicle is provided, comprising an internal combustion engine including an exhaust system; a first turbine including a first wastegate and arranged along a first branch of the exhaust system, a second turbine including a second wastegate and arranged along a second branch of the exhaust system; a first exhaust gas sensor arranged along the first branch of the exhaust system downstream of the first turbine and first wastegate; a second exhaust gas sensor arranged along the second branch of the exhaust system downstream of the second turbine and the second wastegate; and a control system configured to command the first and second wastegates to a closed or open position and to indicate one of said wastegates as unresponsive to said command in response to a temperature difference between the first and second branches indicated by the first and second exhaust gas sensors.