How to Fix / Troubleshooting

Safety first: Flue components can be extremely hot and carry combustion gases. Only trained personnel should open the flue system.

Reset and monitor: After a reset, observe if the error appears immediately or only when the burner fires.
Visual cable check: With power off, inspect the flue gas sensor cable where visible inside the boiler. Look for melted insulation or chafing.
Do not remove flue parts: Flue integrity is critical for safety. Do not dismantle the flue or sensor pocket yourself.
Technician replacement: A Nibe technician will replace the Nibe flue gas temperature sensor and verify flue gas temperatures and combustion.

Boiler indicates sensor short-circuit or over-temperature on flue gas sensor

Possible Causes