Error L6

Safety precautions:

1. If you smell gas, evacuate the property immediately and call the gas emergency number for your area — do not operate electrical switches or the boiler. 2. Do not attempt to open the boiler casing or work on gas or electrical components unless you are a Gas Safe (or equivalent) registered engineer. 3. Limit resets — too many restarts in a short time can create an LC lockout. Turn the boiler off and leave it off while you arrange help if the fault persists.

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

1. Note the exact error code, when it occurs (on demand, at standby, intermittently), and any other symptoms (no hot water, no CH, unusual noises, water leak, smell). 2. Reset the boiler once using the control panel reset button or per the manual. Wait and see if it fires and stays running. 3. Check the gas supply: confirm other gas appliances are working and that the gas meter isolation valve is in the ON position. 4. Check the electrical supply: ensure the boiler has power and that no fuses/trips have occurred. 5. Check system water pressure on the boiler gauge and top up if it is clearly low (follow the boiler manual for repressurising to the recommended level, usually about 1–1.5 bar). 6. Look externally for obvious issues you can safely observe: signs of water leaking from the boiler, loose external wiring, evidence of disturbance around the flue terminal (birds/nests), or blocked flue termination.

Specific diagnostic steps and sensible fixes to try (if you are not opening the boiler):

1. Single reset: press the reset and allow the boiler to attempt ignition. If it starts and runs normally for several cycles, monitor for recurrence. 2. Gas check: confirm gas supply at the meter and the yellow isolation valve under the boiler is in the ON position. If multiple gas appliances are off, contact your gas supplier. 3. Power cycle: if a simple reset does not clear it, switch the boiler off at the isolator/fuse spur for 30 seconds and back on, then try a restart. 4. Observe for patterns: does L6 occur only on CH demand, only on DHW demand, or randomly? Does it happen during/after power cuts or storms? Record occurrences and any sounds (fan running, gurgling, banging) — useful info for the engineer. 5. Check for visible damage or water ingress around the boiler casing or wiring; if you see wet boards, scorch marks or loose connectors do not attempt internal repairs — power down the boiler and call an engineer.

When to call a professional and what to tell them:

1. If the fault remains after a single reset and power cycle, or if it keeps returning, contact a Gas Safe registered engineer (or your manufacturer service) — L6 commonly needs professional testing of flame detection, gas valve function, gas pressure, fan and air pressure switch operation, and the PCB. 2. Provide the engineer with the boiler model, serial number, exact error code (L6) and a description of when it occurs and what you tried (reset, checked gas supply, pressure). 3. If you observed water damage, loose wiring, blocked flue, or other visible issues, tell the engineer – these are often relevant to the cause.

Important final notes:

1. Do not try to adjust or replace the gas valve, ignition electrode, flame sensor, fan, air pressure switch or PCB yourself — these are gas/electrical safety critical parts and must be handled by a qualified engineer. 2. Avoid repeated reset attempts; persistent fault requires diagnosis. 3. If the boiler is under warranty or a service plan, contact the manufacturer or your cover provider and arrange an authorised visit. 4. If you are in the UK, ask for a Gas Safe registered engineer; in other countries contact your national qualified gas engineer service.

Calling a professional is recommended if the simple homeowner checks above do not clear the fault; diagnosing L6 often requires instruments and safe testing of gas and ignition components that only a qualified engineer should perform.