Ferroli boiler fault codes: the verified i25 and i29 list

What do Ferroli fault codes mean?

A Ferroli fault code names the part that stopped the boiler, and the letter tells you how serious it is. Codes beginning with A cause a permanent shutdown: the boiler stays locked out until the reset button is held for one second, and if it still fails to start, the fault has to be eliminated first. Codes beginning with F cause a temporary shutdown that resets automatically once the value returns to the boiler's normal working range. Of the 20 codes below, only F37 is one most householders can reasonably deal with themselves.

The source used here is Table 9, headed "List of faults", on page 10 of the Ferroli i25 and i29 installation manual (cod. 3541I730, Rev. 02, 11/2016). Every code, meaning and cause below is taken from that table. Ferroli does not publish the same list on a homeowner page, so third-party versions circulate and they do not always match the manual.

This is the code set for the Ferroli i25 and i29 combi boilers only, and it is the scope of this page. Other Ferroli ranges use their own, longer tables, and the same number can mean something different: the Bluehelix Prima manual gives F34 as supply voltage under 180V, while the i25 and i29 manual gives F34 as supply voltage under 140VAC. If you have a Bluehelix, Modena, Optimax or any other Ferroli range, read the fault table in your own manual rather than this one.

Every verified Ferroli i25 and i29 fault code

Which Ferroli codes can you safely act on yourself?

Ferroli names three things to check before calling anyone out. Its UK boiler documentation puts it plainly: "to avoid incurring unnecessary expense, in the event of a boiler shut down, check this is not caused by lack of electricity supply, gas supply or low water pressure before calling our Customer Service Helpline."

1. Water pressure, which covers F37 and helps with F43. Read the gauge. The i25 and i29 manual gives a minimum working pressure in heating of 0.8 bar. If it reads low and your system has a filling loop, top up to the cold filling pressure in your own boiler's instructions. The manual also gives 3 bar as the maximum working pressure in heating: that is a ceiling the safety valve protects, never a figure to fill towards. Pressure that falls again within days points to a leak, which needs an engineer.

2. Gas supply, which covers A01 and A06. Check the gas is on at the meter, that a prepayment meter has credit, and that your other gas appliances light. Gas pressures, the gas valve and the electrodes are only for a Gas Safe registered engineer.

3. Electricity supply, which covers F34. Check the switch on the fused spur feeding the boiler is on and that the boiler is not run off an extension lead. Do not open the spur or change its fuse yourself. A genuinely low supply is an electrician's job, not a boiler repair. F35, faulty mains frequency, is the exception: there is nothing you can check or influence at home, so the electrical system has to be tested.

One more rule, and it is ours rather than Ferroli's: reset A codes once only. The reset control is the summer and winter mode button on the control panel. Hold it for one second, once. F codes do not need resetting, and repeatedly resetting an A03 overtemperature fault is exactly the wrong move.

That is where safe stops. Six codes give you something to check: A01, A03, A06, F34, F37 and F43. The other 14 codes mean opening the casing to test a sensor, an electrode, the gas valve, the flue or the control card. Ferroli is blunt: "In case of a fault and/or poor operation, deactivate the unit and do not try to repair it or directly intervene. Contact professionally qualified personnel." The homeowner versus engineer split here is our judgement, not Ferroli's.

When to call a Gas Safe registered engineer

Call an engineer if a code returns after one reset, if it is one of the 14 codes we have marked as engineer work, or if pressure keeps dropping after a refill. Ferroli's manual says any repair must be carried out by qualified personnel using original replacement parts. A01, A06, A09 and A16 touch the gas train, so treat those with most care.

If you smell gas, hear gas escaping or suspect carbon monoxide, do not wait for an appointment. Call the National Gas Emergency Service on 0800 111 999 straight away, open the windows, turn the gas off at the meter if it is safe to reach, leave the electrical switches alone and get out of the property.

For a code on your display today, the route is a one-off repair, which you can book with us on 0333 772 6247. A one-off repair carries a £95 call-out fee, paid in advance, which covers the visit and the diagnosis, and parts and further labour are quoted before any work goes ahead. One-off repair appointments run Monday to Friday, 09:00 to 17:00, and one-off repairs do not carry a workmanship guarantee.

A Smart Plan boiler and central heating module is the separate, ongoing route. It covers future breakdowns rather than a fault your boiler is already showing, so it will not fund the code on your display today. It covers parts and labour up to £500 per 12-month period if your boiler is under 7 years old, or up to £200 if it is over 7. That is one annual limit shared across every fault in the 12-month period, so a larger repair can cost more than the cover pays and you pay the difference. Under a cover plan we aim to get an engineer out to you within two working days, which is a target rather than a promise, and cover-plan call-outs run Monday to Friday, 08:00 to 18:00 unless it is a genuine emergency breakdown. A £95 call-out fee, paid in advance, applies in your first 30 days, for faults the plan does not cover, no-access visits and early annual-service requests, and cover still applies during those first 30 days. Using a service starts a 12-month agreement period, and leaving early after that costs the remaining months or 75% of the outstanding balance. There is a 14-day cooling-off period, which ends the moment a service is carried out. Smart Plan is a service plan, not insurance.

Ferroli fault code FAQs

Ferroli code still showing?

Book a one-off repair with a Gas Safe registered engineer, Monday to Friday, 09:00 to 17:00, with a £95 call-out fee paid in advance and no workmanship guarantee. Or set up a Smart Plan boiler and central heating module so future covered repair costs are paid up to your limit: up to £500 per 12-month period if your boiler is under 7 years old, or up to £200 if it is over 7, as one annual limit shared across every fault. Cover-plan call-outs run Monday to Friday, 08:00 to 18:00, a £95 call-out fee applies in your first 30 days and in the other cases set out in your terms, and using a service starts a 12-month agreement period, with early exit costing the remaining months or 75% of the outstanding balance. Smart Plan is a service plan, not insurance, so it funds covered repairs rather than paying out a cash sum. Call 0333 772 6247.

Helpful links

• Boiler fault codes by manufacturer
• Home repairs and one-off call-outs
• Book a boiler repair
• No heating? Book a repair
• Build your own cover
• Boiler & central heating cover
• More boiler guides on the blog
• Check an engineer on the Gas Safe Register
• Ferroli UK (manuals and support)
• HSE guidance on domestic gas safety