Boiler shows E07, fan may not start, or starts and stops repeatedly.

Safety: Switch off power and ensure the boiler is cool. Risk of flue gas leakage if misrepaired.

• Inspect pressure tubes: Remove the silicone tubes from the air pressure switch and fan. Blow through them to ensure they are clear. Replace if brittle or cracked.
• Check switch contacts: With a multimeter, verify that the pressure switch changes state (open/close) when you gently blow into the high-pressure port. If it does not, replace the switch.
• Clean flue path: Check the flue and air intake for obstructions. Clean any debris from the fan housing and flue connection.
• Verify fan speed: When calling for heat, observe if the fan ramps up to full speed. If it only hums or turns slowly, the fan motor may be failing.
• Reset and test: After cleaning and replacing faulty parts, reset the boiler. If E07 persists, the control board’s fan/APS circuit may require professional diagnosis.