Error L6

Safety precautions:

1. Do not attempt internal repairs to the boiler or gas components unless you are a qualified Gas Safe engineer. Working on gas or sealed electrical parts is dangerous and illegal for unqualified people.

2. If you smell gas at any time, leave the property immediately, do not operate electrical switches, and call the gas emergency number for your area.

3. Isolate the boiler electrically at the fuse spur before opening any covers for visual inspection. If you are unsure how to do this safely, do not proceed and call a professional.

Initial homeowner checks you can do safely:

1. Note the exact error code and any other codes or symptoms. Take a photo of the display for the engineer.

2. Try a simple reset: press the boiler RESTART button or switch the boiler off at the isolator, wait 30–60 seconds, then switch back on and try to restart. If the code clears and the boiler runs, observe for recurrence — if it returns, further investigation is needed.

3. Check that other gas appliances in the house work (hob, gas fire) to confirm gas supply to the property is present.

4. Look around the boiler for obvious signs of water ingress, corrosion, burned components, or loose wires on accessible external terminals (do not open the casing if you are not qualified). If you see water on the electronics or heavy corrosion, note it and call an engineer.

5. If the boiler has had recent power surges, electrical work, or a PCB/chip card change, make a note of that for the engineer as it can be relevant.

If the fault persists or returns after reset, call a Gas Safe registered heating engineer. When you contact them, give them the exact model and error code L6 and describe any steps you have already taken.

What an engineer will check and do (for information):

1. Verify the fault history and repeat the diagnostic run. Use service tools to observe the ignition and flame detection sequence.

2. Inspect and test the flame sensing electrode/ionisation probe and its wiring for correct position, continuity, clean contact and secure connections. Replace the electrode if damaged or faulty.

3. Check wiring and connectors for the flame detection circuit, earth/ground connections, and any signs of corrosion or water ingress.

4. Test the gas valve operation and ignition timing to ensure the valve opens and flame establishes when expected; measure gas pressure at the appliance if needed.

5. Test the printed circuit board and flame sensing circuitry; where applicable check the boiler chip card (BCC) configuration and compatibility. Replace or reprogram PCB/BCC if confirmed faulty.

6. Look for sources of electrical noise, loose earths, or external influences that could create false flame signals.

7. After repairs or component changes, run the boiler through several cycles to confirm the fault is cleared and that there is no intermittent behaviour.

Final notes and when to call a professional:

- L6 is a safety lockout and while basic resets and supply checks are reasonable for a homeowner, component testing, replacement of electrodes, gas valve checks and PCB work must be carried out by a Gas Safe registered engineer. Do not continue to reset the boiler repeatedly; repeated resets can hide an intermittent fault and may create unsafe conditions.

- When you call the engineer, provide the boiler model, L6 code, any other codes shown, recent servicing history, and whether other gas appliances are working. This information helps speed diagnosis and repair.