Boiler
F11
The F11 error code on a Ferroli boiler indicates a flame failure — the boiler is attempting to ignite but cannot establish or maintain a stable flame. This fault will lock out your boiler and stop heating and hot water, so it needs prompt attention.
What does this error mean?
F11 means your Ferroli boiler tried to light but the control board received no signal back from the flame sensor (ionisation probe) confirming a flame was present. The boiler makes a set number of ignition attempts, fails to detect a flame each time, and then locks out as a safety measure. It will not restart automatically — you must intervene.
Est. repair cost
£80–£150 for an ionisation probe or electrode replacement; £200–£400 for a gas valve; £60–£100 call-out fee applies in most cases
🔍 Likely causes
🛠️ Step-by-step fix
Check your gas supply first — confirm other gas appliances in your home (cooker, gas fire) are working. If nothing runs on gas, contact your gas supplier immediately; do not attempt a reset.
Reset the boiler — press and hold the reset button (usually marked with a flame or ‘R’ symbol) for 3–5 seconds until the boiler attempts to restart. Refer to your Ferroli manual for the exact reset location on your model.
Wait and observe — allow the boiler to complete a full ignition cycle. If it lights and runs normally, monitor it over the next few hours to see if F11 returns.
If F11 returns after one or two resets, stop resetting — repeated lockouts without a successful ignition can indicate a gas or component fault. Continuing to reset without a fix is not helpful and will not resolve the underlying issue.
Do NOT attempt to inspect or clean the ignition electrodes, gas valve, or flue yourself — these components involve live gas pathways and must only be handled 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 successful reset, or if it fails to light at all. Tell the engineer the boiler is displaying F11, that it is going to lockout on ignition, and whether any other gas appliances in the home are affected — this helps them diagnose whether the fault is boiler-specific or a supply pressure issue. Do not keep resetting a boiler that repeatedly fails to ignite.
⚖️ Repair or replace?
For a boiler under 10 years old, repair is almost always the right call — cleaning or replacing an ionisation probe costs relatively little, and even a gas valve replacement is far cheaper than a new boiler. If your Ferroli boiler is over 12–15 years old and has had recurring faults, replacement with a modern A-rated combi boiler (typically £1,800–£3,000 fully installed in the UK) will save on energy bills and future repair costs. For a boiler still within warranty, contact Ferroli directly before instructing an independent engineer.