Furnace displays E07 and stops; may be associated with flue gas or safety issues.

Safety: Turn off power and gas. Flue components can be very hot; allow to cool before touching.

• Check flue terminal and route: Ensure the flue terminal is unobstructed and that the flue pipes are correctly assembled with no sagging or disconnections.
• Inspect flue sensor: The flue gas temperature sensor is usually clipped onto the flue outlet or mounted in a pocket. Check that it is firmly attached and that its wiring is intact.
• Clean heat exchanger (professional task): A heavily scaled or sooted heat exchanger can cause high flue temperatures. This requires removal and cleaning by a qualified Chaffoteaux technician.
• Reset: After basic checks, restore power and reset the furnace. If E07 persists, the flue sensor or control board must be tested and replaced by a professional.