E5 alarm, flue gas temperature too high (for Nibe furnaces with combustion module), burner shuts down

Safety: Combustion systems involve risk of fire and carbon monoxide. If you suspect flue blockage, turn off the unit and ventilate the area. Do not operate the burner until inspected.

• Check flue terminal: From outside, ensure the flue outlet is not blocked by snow, nests, or debris.
• Inspect air intake: Make sure the combustion air intake is clear.
• Reset alarm: After clearing obvious obstructions, reset the E5 alarm. If it returns, stop using the burner.

Further work (cleaning heat exchanger, checking burner settings, replacing flue gas sensor) must be done by a certified combustion technician familiar with Nibe equipment.