Error 11; unit reports flue gas sensor or safety device fault and will not operate.

Safety: Turn off power and do not operate the heater until the flue system is verified safe.

• Check flue for blockage: Inspect the flue terminal and accessible sections for obstructions or damage. Do not modify the flue length or configuration without reference to Immergas installation instructions.
• Inspect flue gas sensor: Locate the flue gas NTC or safety thermostat on the flue hood or pipe. Ensure it is firmly attached and its wiring is intact.
• Reset (if manual thermostat): Some flue safety thermostats have a manual reset button. Press it once the unit is cool. If it trips again, there is likely a flue or combustion issue.
• Replace sensor if faulty: If resistance readings are out of specification, install a new Immergas flue gas sensor.

Warning: Flue gas safety devices protect against carbon monoxide hazards. If you suspect flue or combustion problems, contact an authorized technician immediately.