The fault light of Gsx250 engine is on.

1. Sensor fault: The engine fault light usually lights up, indicating sensor fault. Such as an oxygen sensor, a throttle position sensor, a coolant temperature sensor, etc.

2. Fuel system problems: Fuel system problems may cause the engine fault light to light up. For example, fuel pump failure, high or low fuel pressure, etc.

3. Engine mechanical failure: Engine mechanical failure may also cause the engine failure light to light up. For example, valves, pistons, crankshafts and other components are out of order.