Ferroli A56 Fault Code: Causes, Fixes & Repair Costs
What does the Ferroli A56 fault code mean?
The A56 fault code on a Ferroli boiler signals a calibration error — specifically that the boiler's calibration procedure has not been properly completed or that the flame detection system cannot verify a valid calibration state. Because this is an 'A' code in Ferroli's fault system, it is a hard lockout: the boiler shuts down completely and will not restart without a manual reset. (Ferroli also references this condition as F56 in its blocking-fault format, but when displayed as A56 the boiler will not self-recover.) In practical terms, the boiler's PCB is unable to confirm that the ionisation electrode is correctly calibrated and producing a reliable flame signal, so it locks out as a safety precaution.
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
- Calibration procedure not completed Common
The most frequent trigger for A56 is that the boiler's internal calibration sequence was never properly finished — commonly after a service visit, a component swap, or following a firmware update on the PCB. Without a completed calibration, the control board cannot establish a valid baseline for the flame signal and locks out.
- Incorrectly positioned ionisation electrode Sometimes
Even if the electrode is physically undamaged, if it has been disturbed during maintenance and not returned to exactly the right position within the burner assembly, the flame signal will fall outside the expected calibrated range and trigger the A56 code.
- Damaged or degraded ionisation electrode Sometimes
Over time, the ionisation electrode tip can burn away, crack, or become coated with residue, reducing its ability to detect the flame accurately. A faulty electrode produces an unreliable signal that the PCB cannot match against calibration parameters.
- Faulty electrode wiring or loose connections Rare
Damaged insulation, a loose connector, or a broken wire between the electrode and the PCB can mimic a calibration failure by interrupting or distorting the ionisation signal before it even reaches the control board.
- PCB fault Rare
In a small number of cases the PCB itself develops a fault that prevents it from storing or reading calibration data correctly, causing a persistent A56 even after the electrode and wiring have been confirmed as good.
How to fix it
- Check that the gas supply is turned on and other gas appliances in the property are working DIY safe
Before doing anything else, confirm the gas supply to your home is active. Try a gas hob or check with your supplier. If there is a wider gas outage, the boiler fault may clear once supply is restored and you reset the boiler.
- Attempt a manual reset — once or twice only DIY safe
Locate the reset button on your Ferroli's control panel, usually marked with an 'R' or a flame symbol. Press and hold it for approximately one to two seconds. If the boiler fires up and runs normally, monitor it over the next hour. If the A56 code returns within a short period, do not keep resetting — repeated forced restarts can stress the heat exchanger and fan. A maximum of two or three reset attempts is reasonable before calling an engineer.
- Do not attempt to open the boiler casing or adjust any internal components Gas Safe engineer
The ionisation electrode, burner assembly, gas valve, and PCB are all inside the boiler casing. Any work on these parts must only be carried out by a Gas Safe registered engineer. Removing the casing yourself is unsafe and, unless you hold Gas Safe registration, illegal for gas-related work.
- Contact a Gas Safe registered engineer to inspect and re-run the calibration procedure Gas Safe engineer
This is the most common fix for A56. A qualified engineer will connect appropriate service tools and run the boiler's calibration sequence through the PCB. If the calibration completes successfully and the code does not return, no further parts are needed.
- Engineer to inspect, re-seat, or replace the ionisation electrode Gas Safe engineer
If re-running calibration does not resolve the fault, the engineer will examine the electrode for correct positioning, physical damage, or carbon deposits. A misaligned electrode can often simply be re-seated; a damaged one will need replacing. Electrode replacement is typically a straightforward, low-cost repair on Ferroli models.
- Engineer to check electrode wiring and PCB if fault persists Gas Safe engineer
Should the electrode prove intact and calibration still fail, the engineer will trace the wiring loom from the electrode to the PCB, checking for damaged insulation or loose terminals. If the PCB itself is found to be at fault, a replacement board will be required — a less common but more costly outcome.
Parts you may need
- Ionisation / detection electrode · from £25
- Electrode wiring harness / lead · from £30
- PCB (control board) · from £120
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 £90–£220, depending on the underlying cause.
Frequently asked questions
Will the Ferroli A56 fault clear itself without a reset?
No. Because A56 is an 'A' code — a hard lockout in Ferroli's fault classification — the boiler will remain shut down until you manually reset it. Unlike 'F' codes, which can sometimes clear automatically once the underlying condition resolves, an A lockout always requires intervention. If the code returns after resetting, you need an engineer rather than more resets.
What is the difference between Ferroli fault codes starting with 'A' and those starting with 'F'?
Ferroli uses two broad categories: 'A' codes are lockout faults where the boiler shuts down hard and will not restart without a manual reset. 'F' codes are blocking faults that may clear on their own once the triggering condition goes away, though they can also require a reset. The A56 and F56 both relate to calibration errors, but when your display shows A56 specifically you are in full lockout mode.
How much does it typically cost to fix a Ferroli A56 fault?
Most A56 repairs in the UK fall between around £90 and £220 including an engineer's call-out, diagnosis, and any parts needed. If the fix is simply re-running the calibration procedure the cost will be toward the lower end. Replacing the ionisation electrode adds a modest parts cost and usually keeps the bill well under £200. A PCB replacement is the more expensive scenario and can push costs higher — typically £250–£350 — but this is a less common outcome for this particular fault code.
Is it worth repairing a Ferroli boiler showing A56, or should I replace it?
For a Ferroli under ten years old with no history of repeated faults, repair is almost always the more economical choice, especially as Ferroli parts tend to be competitively priced. If your boiler is over ten to twelve years old and has accumulated several fault codes, it is worth asking your engineer for a replacement quote at the same visit. A useful rule of thumb: if annual repair costs are approaching 30–40% of what a new installed boiler would cost, replacement starts to make better financial sense in the long run.