Boiler displays E13, may continue to run at reduced performance or shut down depending on model.

Safety: Combustion and flue issues are critical. Turn off the boiler and do not operate it if you suspect flue blockage.

• Check flue terminal: From outside, ensure the Atlantic flue terminal is clear and correctly assembled. Look for signs of soot or melting, which indicate overheating.
• Reset and observe: After a reset, if E13 reappears quickly, the flue sensor or flue path is likely at fault.
• Do not modify flue: Do not shorten, extend, or alter the flue yourself. This must comply with Atlantic and local regulations.
• Professional service: A technician should inspect the flue internally, test the flue gas sensor, and verify combustion with an analyzer.