E07
Sime Fan / Air Pressure Switch Fault

Boiler shows E07, fan may not start, ignition sequence does not begin

Advertisements

Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Advertisements

Possible Causes

Failed fan motor, Blocked venturi or flue, Faulty air pressure switch, Split or blocked APS tubes

How to Fix / Troubleshooting

Safety first: Isolate power and gas. Combustion air and flue safety components must only be serviced by qualified personnel.

  • Check flue terminal: From outside, ensure the Sime flue terminal is clear of obstructions.
  • Listen for fan: Turn the boiler back on and call for heat. If the fan does not run at all, suspect the fan or PCB.
  • Inspect APS tubing (engineer task): Remove the case and check the silicone tubes from the fan/venturi to the air pressure switch. Replace if brittle, split, or blocked with condensate.
  • Test fan (engineer task): Verify supply voltage to the fan during start-up. If voltage is present but the fan does not spin or is noisy, replace the fan assembly.
  • Test air pressure switch (engineer task): Use a manometer or continuity tester to confirm the switch changes state when the fan runs. Replace if it fails to operate within specified pressure.
Advertisements

Repair Difficulty

Professional Required 5/5

Required Part

Fan and Air Pressure Switch Assembly
Check Price on Amazon

We may earn a commission from links on this page.

Advertisements