Ferroli A06 Fault Code
The A06 fault means the boiler's PCB cannot confirm the fan is running at the correct speed, or the air pressure switch (APS) has failed to trigger during the flue proving sequence. The boiler refuses to ignite as a flue safety measure.
What is the Ferroli A06 fault code?
The Ferroli A06 fault is triggered when the control board does not receive confirmation from the air pressure switch (APS) after the fan starts. The APS is a safety device that monitors the differential pressure created by the fan — it proves that the flue is clear and exhaust gases can safely escape before ignition is permitted. If the APS does not confirm correct fan speed and flue clearance, A06 is displayed and ignition is blocked. The fault can lie with the fan motor, the APS diaphragm, the connecting hose, a blocked flue, or the PCB. Note: Ferroli fan motors and APS components can have a 3–7 day parts lead time from specialist suppliers.
What causes the A06 fault?
The fan motor degrades over time and may run too slowly to generate sufficient flue draught for the APS to trigger. Fan failure is the most common cause of A06 on older Ferroli units.
A bird nest, debris, or partially obstructed flue will restrict airflow and prevent the APS from making — even if the fan is running at full speed.
A cracked APS diaphragm or failed contacts mean the switch shows A06 even when the fan is running correctly. APS failure is the second most common A06 cause.
A cracked or disconnected rubber hose between the APS and fan assembly prevents the APS from sensing fan pressure, triggering A06.
A blocked condensate trap restricts the exhaust gas path inside the boiler, creating backpressure that prevents the APS from making correctly.
In winter, a frozen external condensate pipe creates backpressure that mimics a flue blockage and triggers A06. Thawing the pipe often resolves this immediately.
What you can safely check yourself
If the flue terminal is safely visible from ground level, check for obvious blockages — birds, debris, or leaves. Do not reach inside the flue terminal.
Pour warm (not boiling) water along the external condensate pipe. Once thawed, attempt one reset. This resolves a significant proportion of winter A06 callouts.
If A06 returns immediately after reset, do not attempt further resets. Call a Gas Safe engineer.
Do not reset the boiler more than once if the fault code returns immediately. Repeated resets without diagnosis can mask a worsening fault.
What needs a Gas Safe engineer
- Test fan motor speed and current draw with a multimeter
- Inspect flue terminal and flue run for blockages or restriction
- Test air pressure switch function and diaphragm integrity
- Inspect APS connecting hose for splits or disconnection
- Clear or replace blocked condensate trap
- Check PCB fan sensing circuit if all other components test correctly
- Note parts lead time — Ferroli fan motors can be 3–7 days from specialist suppliers
Fan faults are common across South London's older housing stock. Many Ferroli Modena and DOMIproject boilers installed across Wandsworth, Merton, Lewisham, Lambeth, Southwark, Greenwich, and Bromley are now 8–12 years old — within the fan motor wear window. Annual servicing includes a fan speed check. Parts note: some Ferroli fan motors and APS components are 3–7 day lead time from UK suppliers.
How much does a A06 repair cost?
Costs below are UK averages. Reion provides a fixed quote after the £80 diagnostic visit — no obligation to proceed.
How to reset a Ferroli boiler showing A06
In winter, check and thaw the condensate pipe first.
Check the flue terminal for visible blockages from ground level.
Press the reset button for 3 seconds.
Listen for the fan starting within 5 seconds of reset.
If A06 returns, call a Gas Safe engineer.
Fan motor replacement costs £200–£380 all in and is generally worth doing on a Ferroli boiler under 8 years old. However, Ferroli fan motors can carry a 3–7 day parts lead time. On a unit over 8–10 years old with a fan fault, Reion will give a clear repair-vs-replace comparison at the diagnostic visit, factoring in parts availability and the unit's overall condition.
Common questions about the Ferroli A06 fault
What does a Ferroli A06 fault code mean?
Can a Ferroli A06 fault be caused by cold weather?
How long does a Ferroli A06 repair take in London?
Is a Ferroli A06 fault dangerous?
Why are Ferroli fan parts sometimes slow to source?
Other Ferroli fault codes
Need a Ferroli engineer in London?
Reion is Gas Safe registered (919881), based in South London, and available 24/7. Fixed price after the diagnostic visit — no hidden charges.
