Ferroli A06 Fault Code: Causes, Fixes & Repair Costs
What does the Ferroli A06 fault code mean?
The A06 code indicates that the boiler's flame detection system has lost the burner flame after ignition — and has done so six or more times within a ten-minute window. Rather than continuing to attempt restarts indefinitely, the boiler locks itself out as a safety measure and displays A06. Because it begins with 'A', this is a manual lockout fault on Ferroli boilers, meaning the boiler will not attempt to fire again until you physically reset it. Codes beginning with 'F' on Ferroli boilers are blocking faults that can clear on their own; A06 will not — a reset is always required, and if the underlying cause is not found, the lockout will simply repeat.
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 incorrectly positioned flame detection electrode Common
The flame detection electrode sits inside the burner chamber and confirms to the PCB that a stable flame is present. If it has drifted out of position, become coated in combustion deposits, or has cracked, it cannot send a reliable signal — so even when the burner lights correctly, the boiler 'thinks' the flame has gone out and shuts down. This is the single most common cause of A06.
- Low gas pressure or interrupted gas supply Common
If the gas pressure reaching the boiler drops below the required level, the burner may light briefly but fail to sustain a stable flame. A supply interruption — perhaps due to a partially closed meter tap or a network outage from your gas supplier — produces the same symptom. Confirming another gas appliance such as a hob is working normally is a quick way to rule this out.
- Blocked or frozen condensate pipe Common
During cold weather the condensate drain pipe, particularly any section running outside, can freeze solid. A blocked condensate pipe causes a build-up of acidic water in the sump, which can destabilise combustion and trigger repeated flame-loss events leading to an A06 lockout. This cause is most relevant between November and March.
- Incorrect gas valve offset or gas valve fault Sometimes
The gas valve controls the precise amount of gas entering the burner. If the valve's minimum or maximum gas rate offset has drifted out of calibration — or if the valve itself is sticking or failing — the burner may receive an inconsistent fuel supply, causing the flame to be unstable or to extinguish shortly after lighting.
- Blocked or restricted flue Sometimes
The flue must allow combustion gases to escape freely and fresh air to be drawn in on balanced-flue installations. A blockage caused by a bird nest, debris, or ice formation at the terminal can disrupt this airflow, starving the burner of oxygen and causing the flame to collapse. Boilers that briefly start and then cut out with a rushing or whirring sound before lockout often point to a flue issue.
- Damaged electrode or burner wiring Sometimes
The high-temperature environment inside the boiler can degrade cable insulation over time. If the wiring to the detection electrode or igniter becomes cracked, shorted, or has a poor connection at a terminal, the flame signal will be intermittent or absent even when the electrode itself is in good condition.
- PCB (control board) fault Rare
If all gas, electrode, flue, and wiring checks come back satisfactory, the PCB may be misinterpreting or failing to receive the flame-sense signal altogether. PCB faults are a less common cause of A06 but should be considered once other components have been ruled out by a qualified engineer.
How to fix it
- Try a gas appliance elsewhere in the property DIY safe
Before resetting the boiler, turn on a gas hob ring or check another gas appliance. If nothing is working, contact your gas supplier — the problem is with the supply, not the boiler. If gas is flowing normally elsewhere, move on.
- Reset the boiler — up to twice DIY safe
Locate the reset button on the boiler's front panel; on most Ferroli models it is labelled 'R' or marked with a flame symbol. Press and hold it for around five seconds until the display changes. Allow the boiler a full minute to attempt ignition. If it locks out again, you may try once more — but do not reset more than twice in quick succession. Repeated forced restarts can damage the heat exchanger.
- Thaw a frozen condensate pipe (winter months only) DIY safe
If the weather is at or below freezing, inspect the white plastic condensate pipe that exits the boiler — usually through an external wall — for signs of ice. If frozen, carefully pour warm (not boiling) water along the pipe to thaw it, working from the outside end inward. Dry the pipe, then attempt a reset. Consider lagging any exposed external section with foam pipe insulation to prevent recurrence.
- Check system pressure is within range DIY safe
Look at the pressure gauge on the boiler front. Most Ferroli boilers operate correctly between 1.0 and 1.5 bar when cold. If it is below 0.8 bar, top it up slowly via the filling loop underneath the boiler until it reads around 1.2 bar, then close the loop valves. Low pressure is not a direct cause of A06 but brings the boiler into better overall health before an engineer visits.
- Inspect the flue terminal for obvious blockages DIY safe
Go outside and look at where the flue exits the building — usually a circular duct on an external wall. Check visually for bird nests, ice, or debris partially blocking the terminal. Do not attempt to dismantle or probe the flue yourself. If you can see a clear obstruction, call an engineer to clear it safely.
- Call a Gas Safe registered engineer to investigate further Gas Safe engineer
If the A06 lockout returns after your checks, a Gas Safe engineer is needed. They will clean and test the flame detection electrode, verify its position relative to the burner, test the ignition circuit wiring, check the gas inlet pressure and valve calibration, inspect the combustion chamber and flue circuit, and assess the PCB if everything else is in order. Do not attempt to adjust the gas valve, replace the electrode, or access internal components yourself — this work is legally required to be carried out by a Gas Safe registered engineer in the UK.
Parts you may need
- Flame detection / ionisation electrode · from £25
- Ignition electrode · from £22
- Gas valve · from £120
- Burner assembly · from £85
- Flue terminal / flue kit components · from £40
- PCB (printed circuit board) · from £220
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 £100–£300, depending on the underlying cause.
Frequently asked questions
Can I keep resetting my Ferroli boiler to clear the A06 code?
You can try up to two resets to see whether the lockout was a one-off event, but if the A06 code returns, stop resetting and call an engineer. Repeatedly forcing the boiler to fire when there is an underlying fault puts stress on the heat exchanger and ignition components, potentially turning a modest repair into a much more expensive one.
How much does it cost to fix a Ferroli A06 fault in the UK?
For the most common causes — electrode cleaning or replacement and minor gas pressure adjustment — expect to pay roughly £100–£180 including a Gas Safe engineer's call-out and labour. If the gas valve needs replacing, costs typically rise to £200–£300. A PCB replacement is a less common outcome but can push the total to £300–£400 or beyond depending on parts availability for your specific model.
Why does my Ferroli boiler show A06 only in cold weather?
A06 appearing mainly during cold spells is a strong sign that the condensate pipe is freezing. The condensate drain carries acidic waste water out of the boiler, and if any external section is unlagged, it can freeze in temperatures below zero. Thawing the pipe with warm water and fitting foam lagging around exposed sections should prevent the problem recurring next winter.
What is the difference between an 'A' code and an 'F' code on a Ferroli boiler?
Ferroli uses two families of fault code. Codes starting with 'F' are blocking faults — the boiler pauses but will attempt to restart automatically once the trigger condition clears. Codes starting with 'A', like A06, are lockout faults — the boiler will not restart under any circumstances until someone physically presses the reset button. If the reset does not hold, the underlying fault must be resolved before the boiler will operate normally again.