Method and system for identifying abnormal valve performance in an internal combustion engine

Systems and techniques for identifying abnormal exhaust valve performance of an internal combustion engine may include receiving exhaust passage temperature signals from a plurality of exhaust passage temperature sensors, each exhaust passage being fluidly connected to one or more exhaust valves of the internal combustion engine, the exhaust passage temperature signals being indicative of respective exhaust passage temperatures. The method may further include comparing one or more of the exhaust passage temperatures, identifying a caution exhaust passage temperature, from one or more of the exhaust passage temperatures, that deviates from one or more of the other one or more exhaust passage temperatures, and outputting an abnormal exhaust valve performance indication based on identifying the caution exhaust passage temperature.