Boiler indicates outdoor sensor fault (for weather-compensated systems), heating curve not followed

Safety first: Turn off power before working on wiring. Outdoor work may require ladder safety.

• Check sensor location: The Nibe outdoor sensor should be mounted on a north or northwest wall, away from direct sunlight and heat sources. If incorrectly placed, readings will be inaccurate.
• Inspect cable: Follow the sensor cable visually where possible. Look for cuts, crushed sections, or joints exposed to moisture.
• Secure connections: At the boiler control board, ensure the outdoor sensor wires are firmly clamped in the correct terminals.
• Temporary operation: Many Nibe boilers can operate with a fixed flow temperature if the outdoor sensor is faulty. Set a manual flow temperature until a technician replaces the Nibe outdoor temperature sensor.