What is a typical reaction when the engine fire system test passes?

When the engine fire system test passes, the typical reaction is the indication that the fire system is functioning properly, which is usually communicated through a display message such as "FIRE SYS OK." This confirmation assures the crew that the safety systems are operational and ready to react in case of an actual fire situation. It serves as a critical check that validates the integrity of the fire detection and suppression systems in the aircraft, ensuring that they are ready to protect the aircraft and its occupants in an emergency.

In this context, while other options might indicate various scenarios associated with engine operations or safety systems, they do not accurately represent the response that is expected from a successful engine fire system test. Thus, the message confirming the system's readiness is the focal point of this reaction.