A helicopter Flight Instructor reported a temporary engine fire warning on initial climb and return to departure airport.

Narrative

While in the left crosswind for Runway XX at ZZZ I experienced a fire indication on the Electronic Pilot Monitor (EPM). My student had controls at the time but I immediately took controls; turned towards the runway; selected the 1 2 intersection to land at. I then contacted Tower and requested priority handling while making a descent down to the runway. While descending approximately 5 seconds after the fire indication went on it went off and remained off. I then landed within 20-30 seconds of getting the indication. Once on the ground I set down and immediately set the throttle to idle. I then pulled the fuel shutoff valve and the mixture. I then switched everything else off; light switches; disengaged the clutch; and then switched off master and strobe after confirming with Tower that the emergency truck was on its way. I then got out of the aircraft. I seen no indication of a fire at all during the event or after walking around; nor did I smell any indication. All engine parameters were green prior to this event occurring; no other indications of anything wrong on pre flight or any other time. Cause: There was a sensor indication on the EPM for fire for approximately 5 seconds. I requested priority handling prior to the sensor indication going out. Mechanics are currently looking into it.Suggestions: As there was no indication of an actual fire aside from the sensor; my assumption is it was a sensor error but that is only speculation so by inspecting the sensor and detecting faults that would prevent this event from occurring. I feel I followed the correct procedure and stayed on the side of safety by electing to request priority handling and make an emergency descent to the taxiway. There was no way for me to confirm a fire visually due to the engine being mounted behind the cockpit.