Furnace shows flow temperature sensor error, no heating operation

Safety: Isolate power and allow the flow pipe to cool before handling the sensor.

• Locate flow sensor: Identify the NTC temperature sensor on the flow outlet of the Hoval furnace (often in a brass pocket).
• Check seating: Ensure the sensor is fully inserted into the pocket and secured with its clip or spring.
• Inspect cable: Follow the cable back to the control board, checking for damage or pulled connectors. Reseat the plug on the board.
• Reset controller: Restore power and clear the error. If the error reappears immediately, the sensor may be faulty and should be replaced.