Ferroli A64 Fault Code: Causes, Fixes & Repair Costs
What does the Ferroli A64 fault code mean?
The A64 code is a secondary lockout that appears when a Ferroli boiler has been manually reset too many times in succession without the underlying fault being resolved. Rather than continuing to attempt ignition indefinitely, the boiler's safety logic steps in and locks the unit out completely until a qualified engineer intervenes. On certain Ferroli ranges — including the DOMIcondens HE 26C and Optimax HE Plus — A64 is grouped with codes A63 and F66 and is linked specifically to a Controller DBM12 fault. On other models it may be recorded as a Controller ABM03B error. In either case, A64 is not itself the root fault; it is the boiler telling you that a different problem (most often ignition failure, a gas valve issue, or a PCB fault) was never properly fixed, and that repeated resets have been used as a workaround. Ferroli uses 'A' prefix codes to denote hard lockouts that require a manual reset, distinguishing them from 'F' prefix blocking faults which can sometimes clear on their own. With A64, further resets will not help — and may cause additional damage.
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
- Ignition failure used as repeated reset cycle Common
The most frequent root cause behind A64 is an unresolved ignition fault — typically an A01 on Ferroli models — where the burner fails to light or the flame sensor cannot confirm a stable flame. Common reasons include no gas reaching the boiler, a fouled or worn ignition electrode, or low gas pressure at the meter. Each failed ignition attempt followed by a manual reset inches the boiler closer to the A64 lockout threshold.
- PCB or controller board fault Common
The boiler's printed circuit board (or the dedicated controller module — DBM12 or ABM03B depending on the model) may have developed an internal fault that prevents normal operation. A faulty PCB can cause repeated lockouts across multiple error codes, and if the homeowner keeps resetting rather than seeking a repair, A64 is the eventual result. This is particularly reported on Modena and Optimax range units.
- Gas valve fault or communication error Sometimes
If the PCB loses reliable communication with the gas valve, or if the valve itself is failing, the boiler will lock out as a safety precaution. The controller interprets the missing or erratic valve response as a dangerous condition and refuses to allow further ignition attempts, contributing to or directly triggering the A64 lockout.
- Wiring loom or connector fault Sometimes
Damaged, loose, or corroded wiring between the PCB, the controller module, the gas valve, or the ignition components can cause intermittent faults that trigger repeated lockouts. On older Ferroli units, connector pins can oxidise and cause signal errors that look like component failures but are actually wiring problems.
- Secondary damage from excessive resets Rare
Repeatedly forcing the boiler to attempt ignition when a fault is present can cause physical wear on the fan and heat exchanger. What begins as a minor ignition issue can escalate into a more serious mechanical fault if the boiler is reset many times without diagnosis, ultimately compounding the A64 situation.
How to fix it
- Stop resetting the boiler immediately DIY safe
A64 specifically means the maximum number of consecutive resets has already been reached. Further reset attempts will not clear the code, may mask diagnostic information the engineer needs, and risk causing additional wear to components such as the fan and heat exchanger. Leave the boiler as it is.
- Check that your gas supply is working DIY safe
Before calling an engineer, confirm that other gas appliances in your home (such as the hob or a gas fire) are working normally. If nothing gas-powered works, contact your gas supplier — there may be a supply interruption in your area. If the supply is fine but the boiler alone is faulting, proceed to the next step.
- Note down any previous fault codes DIY safe
If you can recall or have written down any fault codes that appeared before A64 (such as A01 for ignition failure), pass this information to the engineer when you call. It can significantly speed up diagnosis and reduce your call-out time.
- Call a Gas Safe registered engineer to diagnose the root cause Gas Safe engineer
A64 always requires a Gas Safe engineer. The engineer will use a multimeter and diagnostic tools to trace the underlying fault — checking the ignition circuit, electrode condition, gas valve operation, PCB outputs, and the wiring loom between components. You can verify any engineer's Gas Safe registration at gassaferegister.co.uk before they visit.
- Engineer to inspect and test the ignition components Gas Safe engineer
The engineer will check the ignition electrode and lead for wear, carbon deposits, or incorrect spark gap, and test the flame detection circuit. If these are at fault, replacement is straightforward and relatively affordable compared to other repairs.
- Engineer to test the PCB and controller module Gas Safe engineer
The PCB and any dedicated controller board (DBM12 or ABM03B) will be tested for correct outputs and internal faults. If a wiring loom fault is found first, re-wiring may resolve the issue without a full board replacement. If the board itself has failed, it will need to be replaced with a compatible unit.
- Engineer to check the gas valve and wiring loom Gas Safe engineer
The gas valve and its wiring connection to the PCB will be inspected for faults, corrosion, or communication errors. Depending on findings, the engineer may replace the valve, repair the loom, or recommend a PCB replacement if the valve is receiving incorrect signals from a faulty board.
Parts you may need
- Ignition electrode and lead assembly · from £35
- PCB / main control board (Ferroli compatible) · from £120
- Controller module DBM12 / ABM03B · from £95
- Gas valve (Ferroli compatible) · from £130
- Boiler fan / flue fan assembly · from £90
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 £150–£350, depending on the underlying cause.
Frequently asked questions
Can I reset a Ferroli A64 fault code myself?
Not effectively, no. A64 appears precisely because the boiler has already been reset the maximum number of times without the fault clearing. Pressing the reset button again will not help and may make things worse by causing further wear. The only safe course of action is to stop resetting and call a Gas Safe registered engineer to find and fix the underlying problem.
What was the original fault that caused my Ferroli to show A64?
A64 is a secondary lockout, so the original fault was almost certainly something else — most commonly an A01 ignition failure. Other possibilities include a PCB fault, a gas valve communication error, or a wiring problem. If you noticed a different code appearing before A64, let your engineer know, as it will help them pinpoint the fault more quickly. The engineer's diagnostic check will identify the root cause.
How much will it cost to fix a Ferroli A64 fault?
Most people with an A64 fault end up paying between £150 and £350 all-in, depending on what the underlying fault turns out to be. A diagnostic visit alone typically costs £80–£150. Simple fixes like an ignition electrode replacement sit towards the lower end, while a PCB or gas valve replacement will push costs higher. In rare cases — for instance if the heat exchanger has been damaged by repeated failed ignition attempts — costs can exceed £500, at which point replacing an older boiler may be more economical.
Should I replace my Ferroli boiler if it keeps showing A64?
If your Ferroli is under 8–10 years old and the repair cost is reasonable, fixing it makes sense. However, if the boiler is over 10 years old and repair quotes are approaching 30–40% of what a new boiler would cost, replacement is worth serious consideration. A new A-rated condensing boiler will also be significantly more efficient than an older Ferroli unit, potentially saving money on gas bills over time. A Gas Safe engineer can give you an honest view on whether repair or replacement is the better value decision for your specific model.