Error T6

Safety first:

1. If you smell gas, evacuate the property immediately, do not operate electrical switches, and call the gas emergency number and a Gas Safe engineer.

2. If you suspect carbon monoxide (unusual soot, yellow tipping of the burner, headaches, nausea), turn the appliance off, ventilate the building and call an engineer and/or the emergency services.

3. Isolate power to the boiler before doing any visual or non-powered inspection. Do not open the burner compartment, attempt to adjust the electrode gap, or work on gas wiring or the gas valve unless you are a Gas Safe registered engineer.

Initial homeowner checks (non-invasive):

1. Reset the boiler once using the manufacturer’s reset procedure (consult the boiler manual). Note whether the T6 code returns immediately or after a few attempts to fire.

2. Check mains power and external controls (room thermostat, timer, programmer). Ensure the boiler has a stable power supply and isn’t being inhibited by external controls.

3. Check basic boiler status: water pressure, visible error LED behaviour, and whether other fault codes are present. Record exact fault code(s) and any accompanying messages.

4. Look for obvious signs of moisture or corrosion around the flue terminal, appliance base, and visible wiring/connections. Moisture ingress can affect ignition/electrode behaviour.

5. Ensure condensate pipe is clear/not frozen and the flue terminal is not blocked by debris or nesting birds. Blocked flue or air supply can cause odd combustion/diagnostic behaviour.

Specific diagnostic and safe checks you can do (visual and non-invasive):

1. After isolating mains power, remove the boiler casing only if you are comfortable and the manual allows it for visual inspection. Look for loose or corroded connectors at the ignition electrode lead(s) and at the main control board connector. Tight, clean connections are required for a reliable ionisation signal.

2. Visually inspect the ignition electrode lead for physical damage, chafing, cracks or oil/soot contamination. If the lead or connector looks damaged, DO NOT attempt an electrical repair yourself — note it for the engineer.

3. If the electrode assembly looks wet or contaminated (water, soot), allow the boiler to dry fully (do not apply heat or flame). A short period of dry weather or calling an engineer to dry/replace the electrode is the right approach.

4. Power up and try a reset after any cleaning/inspection that did not involve touching gas components. If the T6 returns immediately, it suggests an electrical/PCB/ionisation oscillator problem rather than intermittent contamination.

5. Note any related fault codes (EA - no ionisation after ignition, FA - ionisation after gas valve closed, F7 - ionisation before burner start). Those give clues: EA typically points to no flame detection (electrode, lead, or gas/ignition issue), FA indicates false flame detection, and F7 indicates detection before burner start (possible wiring or PCB fault).

When to call a professional and what to tell them:

1. Call a Gas Safe registered engineer if the T6 repeats, especially if the boiler locks out, there are related ignition/flame codes (EA, FA, F7), you smell gas, or you’re unsure. Do not attempt to repair ignition/electrode, gas valve, or PCB components yourself.

2. When you call, provide: boiler model, exact fault code(s), whether reset cleared it, how often it happens, any recent works, signs of water/condensate issues, and whether the condensate or flue was blocked or frozen.

3. The engineer will have the instruments and legal competence to test the ionisation oscillator, check electrode voltage and current, inspect/replace electrode and lead, test the ignition unit and gas valve, and if needed replace or repair the control electronics (PCB/HCM). They will also check combustion and flue safety.

Final notes:

- T6 by itself can be a routine test entry, but a persistent or repeating T6 with operational problems requires professional diagnosis. Homeowners should limit themselves to the safe checks listed above and always use a Gas Safe registered engineer for repairs or replacement of ignition, gas or control components. Do not attempt DIY repairs on gas or ignition systems.