Boiler indicates sensor fault on heating circuit 2 or mixing circuit (if equipped)

Safety first: Turn off power before accessing the mixing module or wiring.

• Check sensor attachment: Ensure the sensor is firmly attached to the correct pipe (flow or return) and insulated from ambient air.
• Inspect cable routing: Avoid running sensor cables alongside mains cables to reduce interference and damage risk.
• Verify module connections: At the Nibe mixing module, confirm that sensor wires are in the correct terminals as per the installation manual.
• Professional service: A technician can test and replace the Nibe mixing circuit sensor or module PCB if defective.