Boiler
115
Error code 115 on a Potterton boiler indicates a flame detection fault — the boiler is failing to detect a stable flame after ignition. This is a safety lockout and should not be ignored, as continuing to attempt restarts without diagnosis can mask a more serious underlying problem.
What does this error mean?
The 115 code means the boiler’s control board has tried to ignite the burner but the flame sensor (ionisation probe) has either not detected a flame at all, or detected one too briefly to confirm a stable burn. As a safety measure, the boiler shuts itself down to prevent unburned gas from accumulating. This is a lockout fault, meaning the boiler will not restart automatically — it requires a manual reset or engineer intervention.
Est. repair cost
£150–£350 for a Gas Safe engineer diagnosis and repair (part-dependent); new boiler installation £2,000–£3,000
🔍 Likely causes
🛠️ Step-by-step fix
Check your gas supply first: confirm other gas appliances in your home (hob, gas fire) are working normally. If they are not, call your gas supplier immediately — do not attempt to reset the boiler.
Press the reset button on your Potterton boiler (usually marked with a flame or reset symbol) and hold for 3–5 seconds. Allow the boiler to complete its ignition sequence. One reset attempt is reasonable; do not reset more than twice.
If the boiler fires up but locks out again within minutes, stop resetting. Repeated lockouts on the same fault code point to a component failure that a reset will not fix.
Check that the gas isolation valve on the pipe immediately behind the boiler is fully open (handle in line with the pipe, not across it).
Beyond these steps, do not attempt any further DIY. Error code 115 involves gas and combustion components — all further diagnosis and repair must be carried out by a Gas Safe registered engineer.
📞 When to call a professional
Call a Gas Safe registered engineer if the boiler locks out again after a single reset, if you smell gas at any point, or if you have any doubt about the gas supply. Tell the engineer the boiler is displaying error code 115 and describe how many times it has locked out — this helps them bring the right parts. Do not attempt to inspect the burner, gas valve, or flue yourself.
⚖️ Repair or replace?
A professional repair for a 115 fault typically costs £150–£350 depending on which component has failed — an ionisation probe or electrode is at the lower end, a gas valve or PCB at the higher end. If your Potterton boiler is over 10–12 years old and has already needed repairs, replacement with a modern A-rated boiler (typically £2,000–£3,000 installed) is often better value long-term. For a boiler under 8 years old in otherwise good condition, repair is almost always the right call.