Error F7

Safety precautions:

- If you smell gas or a carbon monoxide alarm is sounding, evacuate the property immediately, call the gas emergency number and 999 if necessary. Do not use electrical switches. Do not attempt repairs.

- Before touching any part of the boiler, turn off the electrical supply at the isolator and at the fusebox. If you are unsure how to do this safely, call a Gas Safe engineer.

- Never attempt to work on gas valves, burner assemblies, or replace ignition or PCB parts unless you are Gas Safe qualified.

Initial checks a homeowner can do (no internal work):

1. Note and photograph the display showing F7 and any flashing lights or cause codes (press the spanner/return/info button if present to capture a cause code). This information is useful to the engineer.

2. Try a controlled reset: follow the boiler manual reset procedure (usually switch off, wait a short period, then switch back on or press/hold the reset for 3 seconds as per your model). Attempt one reset only. If the fault returns immediately or repeatedly, stop and call a professional.

3. Check the external flue terminal (outside) for obvious blockages or damage: bird nests, leaves, debris, or heavy water ingress. Remove loose debris from the terminal area but do not attempt to dismantle the flue. If you find blockage or water inside the terminal, inform your engineer.

4. Check for recent conditions that might have caused ingress or damp (heavy rain, freezing causing condensate blockage). Note if the condensate pipe has frozen or blocked in cold weather.

5. Check when the boiler was last serviced. If overdue for the annual service, book a Gas Safe engineer for a service and full inspection.

Specific diagnostic actions for homeowner (visual, non-intrusive):

- With the electrical supply OFF, look at the boiler front and through any service access if safe to do so for obvious signs of water/damp on the front of the burner area, soot, or corrosion. Do not put your hands inside or probe components.

- If you are competent and confident with electrical isolation and your manual allows it, you can open the front cover to look for obvious water or corrosion on the PCB or wiring but only after isolating the mains. If you see damp or heavy corrosion, DO NOT power the unit back up; call a Gas Safe engineer.

- If an electrode is visibly wet or contaminated from leaks/condensate, do not try to scrub or work on the ignition assembly unless you are qualified. A visual note that the electrode is wet/damaged is useful to pass to the engineer.

What to tell the engineer / evidence to gather:

- Exact fault code (F7) and any three-digit cause code from the information menu if available.

- Whether the fault persists after a reset, and if it recurs immediately or intermittently.

- Any recent events: power cuts, freezing weather, heavy rain, recent plumbing work, or lack of service.

- Photos of the display, external flue terminal, and any obvious corrosion or damage you observed.

When to call a professional:

- If the fault remains after a single reset, if it recurs, or if you find any signs of water ingress, corrosion, broken/damaged flue terminal, or damaged wiring.

- If you are uncomfortable isolating power or opening the boiler cover safely. Repairs to electrodes, flame sensor, wiring, or the PCB must be carried out by a Gas Safe registered engineer.

- If there is any suspicion of gas leak or carbon monoxide, call emergency services and your gas supplier immediately.

Likely work the engineer may carry out (for information only):

- Run diagnostic checks, read cause codes, test the flame sensor circuit and ignition electrodes, check wiring continuity and earth/insulation, inspect the flue for water ingress or blockage and the condensate route, and test the PCB inputs/outputs. They will replace faulty electrodes, leads, or PCB modules if required and carry out a safety gas-tightness and combustion check.

Summary: perform basic, non-intrusive checks (reset once, inspect external flue, note cause codes and symptoms). Do not attempt internal gas or electrical repairs. If the fault persists, call a Gas Safe registered engineer to diagnose and fix the root cause.