Error Slow flash ( mostly off flashes on)

Safety precautions:

- If you smell gas, leave the property immediately, do not operate electrical switches or the boiler, turn off the gas at the meter if safe to do so, and call the national gas emergency number and your gas supplier. If you or anyone has symptoms of carbon monoxide poisoning (headache, nausea, dizziness), get fresh air and seek emergency help.

- Do not open the boiler casing or attempt to repair gas or high-voltage components unless you are a Gas Safe-registered engineer.

- Only perform visual and external checks; avoid touching internal parts or connectors.

Initial homeowner checks (non-invasive):

1. Record what you see: note the slow-flash, any triangle or fault symbol, and any three-digit cause code shown in the information menu. Take a clear photo of the display; this helps the engineer.

2. Try a controlled reset: press and hold the boiler reset button (or follow the reset procedure for your model) for about 3 seconds. Wait to see if the boiler attempts to light and stays running. Do not attempt more than 2 or 3 resets in succession — repeated resets won’t fix an underlying fault.

3. Check that other gas appliances (hob, oven) are working. If they are not, this suggests a mains gas supply or meter issue — contact your gas supplier.

4. Make sure mains power to the boiler is on and the house fuse/MCB hasn’t tripped. Confirm the boiler’s power switch and any external programmer/thermostat are calling for heat.

5. Inspect the external flue terminal for obvious blockages (nests, heavy debris) from outside. If you see a blockage, do not poke inside the flue; note it and tell the engineer.

6. If the boiler has been recently serviced or there’s been water ingress, check whether the ignition area/electrode could be wet. Do not open the casing; simply note recent events and whether the boiler was exposed to damp.

Specific diagnostic steps to collect useful information:

1. Access the boiler information menu (use the spanner/return button if your model has it) and write down both the displayed fault code and the cause code. These are essential for the engineer.

2. Note any related symptoms: noisy fan on startup, faint smell of gas when trying to light, the boiler attempting several ignition cycles then locking out, or any other fault codes visible in the menu.

3. If you are competent and only for visual confirmation (do not touch internal parts): check that visible ignition leads and connectors (external, not inside the sealed casing) are not loose. If a connector looks detached externally, do not reconnect unless you know what you’re doing — instead report this to the engineer.

4. If the electrode area may be wet from condensate or a leak, allow time to dry and try a single reset later. Report any evidence of water or leaks to the engineer.

When to call a professional and what to tell them:

- Call a Gas Safe-registered engineer whenever the boiler shows an ignition lockout, unless a simple issue like the gas supply being off or a clearly visible external flue blockage is the confirmed cause. Do not attempt internal repairs, gas valve checks, or ignition-electrode replacements yourself.

- When you call, provide: the exact fault display (slow flash/ignition lockout), any fault and cause codes from the information menu, what happens when you press reset, whether other gas appliances work, whether you smelled gas, and any recent events (power cut, servicing, water leak).

- If you detect a gas smell or suspect a leak, treat this as an emergency: evacuate, call the gas emergency number and do not use the property until checked.

Additional notes:

- Repeatedly resetting the boiler without addressing the underlying cause is not recommended; the lockout is a safety action. The engineer may need to test ignition voltage, ignition electrode condition and gap, gas valve operation, fan function, wiring and PCB, and the flue and sensors to find the root cause.

- Keep a record of error codes, photos, and the sequence of events — this speeds diagnosis. A Gas Safe engineer will have the correct tools and permissions to repair or replace ignition-related parts safely.