Boiler
111
Error code 111 on a Potterton boiler indicates a lockout due to ignition failure — the boiler has tried to light and failed, shutting itself down as a safety measure. It’s a moderately serious fault that needs prompt attention, as it means you have no heating or hot water.
What does this error mean?
The 111 code tells you the boiler’s control board attempted to ignite the burner but received no confirmation from the flame detection sensor that ignition was successful. Potterton boilers are programmed to lock out after a set number of failed ignition attempts to prevent unburned gas from building up. This is a safety lockout, not a component that has simply switched off.
Est. repair cost
£80–£250 for a Gas Safe engineer repair (parts and labour); new boiler replacement £1,500–£2,500 installed
🔍 Likely causes
🛠️ Step-by-step fix
Step 1 — Reset the boiler: Press and hold the reset button (usually marked with a flame or ‘R’ symbol) for 3–5 seconds. The boiler will attempt to re-ignite. Stand by and listen for a clicking ignition sound followed by the burner lighting.
Step 2 — Check your gas supply: Confirm other gas appliances in your home (e.g. a gas hob) are working normally. If they’re not, contact your gas supplier immediately — do not attempt to reset the boiler again.
Step 3 — Check your gas meter: Ensure the meter’s isolation valve is fully open (handle inline with the pipe = open). If you have a prepayment meter, check you have credit.
Step 4 — Attempt a second reset after 10 minutes: If the first reset failed, wait 10 minutes and try once more. If the boiler locks out again with code 111, stop here — further resets without fixing the root cause will not help.
Step 5 — Do not attempt further DIY: All remaining causes (flame sensor, ignition electrode, gas valve, PCB) involve gas components and must be diagnosed and repaired by a Gas Safe registered engineer. This is a legal requirement in the UK.
📞 When to call a professional
If the boiler locks out with code 111 after two reset attempts, call a Gas Safe registered engineer straight away. Tell them: ‘My Potterton boiler is showing error code 111, it’s locking out on ignition failure, and resetting hasn’t resolved it.’ Do not repeatedly reset the boiler — this can mask the fault and, in rare cases, risk a gas build-up.
⚖️ Repair or replace?
A Gas Safe engineer call-out plus repair typically costs £80–£250 depending on the faulty part — an ignition electrode or flame sensor is at the cheaper end, while a gas valve or PCB replacement pushes toward the top of that range. If your Potterton boiler is over 10–12 years old and this is not its first significant fault, replacement is worth serious consideration — a new A-rated combi boiler costs £1,500–£2,500 fully installed and will be far more efficient. For a boiler under 8 years old in otherwise good condition, repair is almost always the right call.