Boiler
131
Error code 131 on a Potterton boiler indicates a flame detection fault — the boiler is either failing to ignite or losing its flame shortly after lighting. This is a safety lockout and needs prompt attention, though a simple reset is always the right first step.
What does this error mean?
The 131 code means the boiler’s control board has detected that the burner flame either didn’t establish or cut out unexpectedly during a heating or hot water demand cycle. The boiler locks out as a safety measure to prevent unburned gas from accumulating. Until the underlying cause is resolved, the boiler will not fire up and your heating and hot water will be off.
Est. repair cost
£100–£300 for a Gas Safe engineer repair (parts and labour); condensate thaw is free DIY
🔍 Likely causes
🛠️ Step-by-step fix
Check your gas supply first: turn on a gas hob or another gas appliance. If nothing works, call your gas supplier — the fault is not with the boiler.
Inspect the condensate pipe (the white plastic pipe usually running to an external drain or gulley). If it’s frozen solid or blocked, carefully thaw it with warm (not boiling) water and a hot water bottle. This is a safe DIY task.
Press the reset button on your boiler — usually a flame icon or a button labelled ‘Reset’. Hold it for 3–5 seconds. Allow the boiler a full minute to attempt ignition.
If the boiler locks out again immediately or within one or two reset attempts, stop resetting it. Repeated failed ignition attempts can allow unburned gas to build up — do not continue cycling the reset.
Check your boiler pressure gauge (visible on the front panel). If pressure is below 1 bar, top up via the filling loop following your boiler manual. Low pressure alone rarely causes code 131 but can contribute to ignition issues.
If none of the above resolves the fault, do not attempt to open the boiler casing or touch internal components — call a Gas Safe registered engineer.
📞 When to call a professional
Call a Gas Safe registered engineer if the boiler locks out again after one or two resets, or if you smell gas at any point (in which case: stop, ventilate the room, and call the National Gas Emergency line on 0800 111 999 immediately). Tell the engineer you have a Potterton boiler showing fault code 131 — this lets them know it’s a flame detection lockout and they’ll come prepared with an ionisation electrode and gas valve testing equipment.
⚖️ Repair or replace?
A Gas Safe engineer call-out typically costs £80–£120, with parts like an ionisation electrode (£20–£50) or gas valve (£100–£200) on top, putting most 131 fault repairs in the £100–£300 range. If your Potterton boiler is over 10–12 years old and has needed repeated repairs, replacement with a modern A-rated condensing boiler (typically £1,800–£3,000 installed) is likely more cost-effective long-term. For a boiler under 8 years old in otherwise good condition, repair is almost always the right call.