Error 6 green flashes

Safety precautions:

1. If you smell gas, hear a hissing sound, or suspect a gas leak, get everyone out of the building immediately and call your local gas emergency number. Do not operate electrical switches or the boiler. Do not attempt repairs.

2. If you are in any doubt about safe operation, stop and call a Gas Safe registered engineer. Do not remove the boiler casing or attempt internal repairs unless you are qualified.

3. Isolate the boiler from mains power using the external isolation switch before touching any external plumbing or electrical connections.

Initial checks a homeowner can do (safe, non-intrusive):

1. Record the exact behaviour: time, how long the flashes last, whether the boiler tries to restart, and any other lights or messages. Note model and serial if visible.

2. Check the boiler pressure gauge: normal is approximately 1.0–1.5 bar when cold. If the pressure is low (under ~0.8–1.0 bar) this can cause intermittent errors—top up via the filling loop if you are comfortable doing so and you know how.

3. Check that the boiler has power (external switch or fused spur) and that any household fuses have not tripped.

4. Confirm the gas supply is on (check meter or prepayment credit if applicable). If you suspect a supply issue contact your gas supplier.

5. Look for obvious external problems: blocked flue terminal (leaves, bird nest), frozen condensate pipe in cold weather (usually outside), or visible water leaks around the boiler or system.

6. Bleed a radiator or two if you suspect air in the system; then re-check pressure and top up if it has dropped.

Specific diagnostic and basic fix steps you can try:

1. Try a controlled reset: locate the boiler reset button or selector (often marked 'reset' or a flame symbol, or use the selector switch set to R). Press and hold for 5–10 seconds, then release. Allow the boiler several minutes to attempt a normal restart.

2. After reset, watch the boiler for the next 10–15 minutes while calling for heating/hot water to see if it runs normally or re-displays the 6 green flashes.

3. If the error clears and the boiler runs, monitor for recurrence over the next 24–48 hours. One isolated occurrence that self-clears is usually not a concern.

4. If pressure was low and you topped it up, re-check that pressure remains stable. If pressure repeatedly drops it indicates a leak or faulty component and you should call an engineer.

5. If the condensate pipe is frozen, thaw it gently with warm (not boiling) water or a hot water bottle and reattempt a restart.

6. If you see additional or changing flash patterns (red flashes, repeated lockouts) or if heating/hot water remains unavailable after reset, stop further resets and contact a professional.

When to call a professional and what they will check:

1. Call a Gas Safe registered engineer if the 6-green error returns repeatedly, if the boiler will not restart after a reset, if you observe red fault flashes, or if heating/hot water remain unavailable.

2. An engineer will connect diagnostic tools or read the boiler action log, check the PCB and parameter storage, test sensors (NTC thermistors), inspect the fan and combustion unit, check the gas valve and ignition components, and examine wiring and connections.

3. Do not continue to repeatedly reset the boiler as a long-term fix; repeated resets can hide a developing fault and may cause further damage.

Final notes:

1. Treat a single, self-clearing 6-green flash as a low-severity, temporary event but log it and watch for recurrence.

2. If the fault becomes persistent or is accompanied by other fault indicators (red flashes, loss of function), arrange an engineer visit and provide them with the model, serial, time stamps and the exact flash pattern to speed diagnosis.