Methods and systems are provided for detecting an overspeed shutdown condition of an internal combustion engine. The pressure within an air-intake manifold of the engine is measured, and that pressure is compared to a predetermined pressure, which represents the pressure within the air-intake manifold when an overspeed-shutdown mechanism has not been activated. Activation of the overspeed-shutdown mechanism is indicated when comparing the measured pressure value to the predetermined value results in the measured value being less than the predetermined value.