What indicates an amber ENG BLEED FAULT light?

The amber ENG BLEED FAULT light is an essential indicator in the A320 aircraft, specifically related to the operation of the engine bleed air system. The correct interpretation of this light is that it indicates a fault condition with the engine bleed valve, particularly when the valve is not closed while the APU bleed valve is open.

When the APU (Auxiliary Power Unit) is in operation and providing bleed air, the engine bleed valves should be closed to prevent any backflow or inadvertent operation that could lead to system inefficiencies or conflicts. If the engine bleed valve remains open while the APU is providing bleed air, the amber ENG BLEED FAULT light is triggered, alerting the crew to this potential issue that could affect the aircraft's pneumatic system operations. This condition could lead to increased wear or a hazardous situation if not corrected.

The other choices pertain to different scenarios that do not specifically relate to the failure of the engine bleed valve being in an open state while the APU bleed is active. Understanding the function and conditions that trigger the ENG BLEED FAULT light is crucial for effectively managing the system during various phases of flight.