Ferroli A24 Fault Code: Causes, Fixes & Repair Costs
What does the Ferroli A24 fault code mean?
The A24 fault code on a Ferroli boiler indicates a card parameter error — meaning the boiler's control board (PCB) has detected a problem with its own internal settings or configuration. In plain terms, the boiler's electronic brain has either lost its programmed parameters, encountered a configuration mismatch, or detected a hardware fault within the board itself. Because the PCB governs virtually every function of the boiler, this fault causes the boiler to lock out as a safety precaution. A24 is closely related to other PCB-type codes on Ferroli boilers — including A23, A26, F15, F20, F21, F40, F47, F50, F51, and F53 — all of which point to control board or parameter issues. Some sources also group A24 alongside F04 and F07 under the broader category of electronic board faults. Whatever the precise trigger, A24 almost always requires a Gas Safe engineer to investigate and resolve.
General guidance only — not a substitute for professional advice, and not certified by a Gas Safe engineer. Always have your specific appliance assessed by a qualified professional. Any gas work must be carried out by a Gas Safe registered engineer. If you smell gas or suspect carbon monoxide, leave the property and call the National Gas Emergency line on 0800 111 999.
Common causes
- Faulty or failing PCB Common
The most common cause of A24. The control board itself may have developed an internal fault — perhaps due to age, component failure, or damage from a power surge — meaning it can no longer correctly read or retain its operating parameters. This requires professional electrical testing and likely PCB replacement.
- Corrupted or incorrect parameter settings Common
The PCB stores configuration data that tells the boiler how to behave. A power cut, voltage spike, or firmware corruption can scramble these stored values, triggering the A24 error even if the board hardware is physically intact. An engineer may be able to reset or reprogram the parameters without replacing the board.
- Wiring fault to the control board Sometimes
Loose, corroded, or damaged wiring connections between the PCB and other boiler components can cause erratic signals that the board interprets as a parameter error. An engineer will check all harness connections and test continuity with a multimeter before concluding the board itself needs replacing.
How to fix it
- Reset the boiler once or twice DIY safe
Locate the reset button on your Ferroli boiler — it is usually marked with an 'R' or a flame symbol. Press and hold it for around 5–10 seconds. If the boiler fires up and runs normally, the error may have been a one-off glitch caused by a momentary power fluctuation. Do not reset more than two or three times; if the A24 code keeps returning, repeated resets will not fix the underlying fault and may cause additional wear.
- Check your household gas supply DIY safe
Confirm that other gas appliances in your home — such as a hob or gas fire — are working normally. If they are not, the issue may be with your gas supply rather than the boiler. Contact your gas supplier if you suspect a supply interruption.
- Do not attempt to access or modify the PCB Gas Safe engineer
The PCB is an internal electrical component and working on it requires Gas Safe registration. Do not open the boiler casing, disconnect wiring, or attempt to reprogram any settings yourself. Doing so is unsafe and will invalidate any remaining warranty.
- Call a Gas Safe registered engineer to diagnose the fault Gas Safe engineer
A qualified engineer will open the boiler, inspect the PCB and its wiring harness, and use a multimeter to check for breaks or shorts in the circuit. If wiring is the culprit, a straightforward repair may resolve the fault. If the board itself is faulty, it will need to be replaced with a compatible Ferroli PCB. Ask the engineer to confirm the part number before ordering, as availability on older Ferroli models can vary.
- Consider whether repair or boiler replacement makes more financial sense DIY safe
If your Ferroli boiler is more than 10 years old and the engineer quotes for a PCB replacement, weigh this against the cost of a new boiler. If the repair cost is approaching 30–40% of a replacement boiler's price, a new, more efficient boiler is often the better long-term investment — particularly given that Ferroli parts for discontinued models can be difficult to source.
Parts you may need
- Ferroli PCB (control board) · from £220
- Wiring harness / connector loom · from £45
- PCB fuse kit · from £12
The exact spare depends on your boiler's GC number (on the data badge). Check this against the part before buying.
Typical repair cost
Expect to pay roughly £120–£350, depending on the underlying cause.
Frequently asked questions
Can I fix the Ferroli A24 fault code myself?
Beyond a basic boiler reset (up to two or three times), there is nothing a homeowner can safely do for the A24 fault. The code relates directly to the PCB — the boiler's main control board — which is an internal electrical component. Any work on it must be carried out by a Gas Safe registered engineer. Attempting to open the boiler or interfere with the wiring yourself is dangerous and will void any remaining warranty.
How much does it cost to fix a Ferroli A24 fault?
A call-out and diagnosis from a Gas Safe engineer typically costs £80–£150. If the fault turns out to be a simple wiring issue, the total repair cost is usually within that range. If the PCB itself needs replacing, most homeowners pay £200–£350 in total including parts and labour. On older or discontinued Ferroli models, the PCB part alone can exceed £300, so the overall bill can sometimes be higher — which is worth factoring into a repair-versus-replace decision.
Why does my Ferroli boiler keep showing A24 after I reset it?
If A24 returns shortly after a reset, there is a genuine underlying fault — most likely a failing PCB or a wiring problem — that a reset cannot cure. Continuing to reset the boiler repeatedly is not advisable, as it does nothing to address the root cause and can put additional strain on components such as the heat exchanger and fan. At this point you should stop resetting and call a Gas Safe engineer to investigate properly.
Is the Ferroli A24 fault the same as A23 or A26?
They are closely related. A23, A24, and A26 are all grouped within Ferroli's PCB and card parameter fault category, meaning they all point towards control board issues. The precise sub-code can help an engineer narrow down whether the problem is a parameter mismatch, a hardware failure on the board, or a communication error — but in practice all three codes are diagnosed and resolved in the same way, and all require a Gas Safe engineer.