Ferroli Boiler Error Codes: Causes & Fixes
Ferroli boiler error codes appear on the display to alert you to a specific issue so you can restore heating and hot water quickly. The most common ones UK homeowners and landlords see are F37 for low system pressure, A01 for ignition failure and F05 for air pressure or fan problems.
These often stem from everyday issues like pressure drops, minor blockages or wear, and many can be resolved with a simple reset or top-up while others need a professional check to keep everything safe and efficient.
Ferroli Boiler Error Codes: Quick Overview
Ferroli boilers use clear error codes (starting with A or F depending on your model) to show exactly what’s wrong and protect the system from damage. Most are straightforward and many homeowners can handle the first steps themselves, while others require a Gas Safe engineer. Here’s a handy reference table of the main codes you’re likely to see:
| Error Code | What It Means |
| A01 | Ignition failure – the boiler cannot light the burner |
| A02 | Flame detected when burner is off |
| A03 | Overheating or heating sensor issue |
| A05 | Fan fault |
| A06 | No flame after ignition attempt |
| F05 | Air pressure switch error |
| F07 | Air pressure switch or high flue temperature |
| A09 / A16 | Gas valve fault |
| F10 | Flow temperature sensor fault |
| F11 | Hot water sensor fault |
| F34 | Supply voltage too low |
| F37 | Low system water pressure |
| F43 | Heat exchanger protection activated (no circulation) |
| F50 / F51 | Control board or controller error |
Newer models like BlueHelix Tech or Modena may show slight variations, but these cover the vast majority of UK installations.
Ferroli Error Code A01: Ignition Failure
Error code A01 on your Ferroli boiler means the burner tried to light but could not detect a flame, so the unit shuts down safely.
What Causes Error Code A01
This is usually due to no gas supply, a faulty ignition electrode, low gas pressure, or excessive condensate in the pipe blocking the burner.
How to Fix
- Check your gas meter and other gas appliances are working.
- Turn the boiler off at the mains for 30 seconds, then switch it back on to reset.
- If the code returns quickly, do not keep resetting – call a Gas Safe registered engineer to check the electrode and gas valve safely.
Ferroli Error Code A02: Flame Detected When Burner Is Off
Error code A02 on your Ferroli boiler signals the system is detecting a flame even though the burner should be off, which is a safety concern.
What Causes Error Code A02
A dirty or faulty electrode, issues with the control board, or poor earthing in the electrical supply are the usual reasons.
How to Fix
- Reset the boiler once.
- If it returns, turn off the gas at the meter and call a Gas Safe engineer immediately to inspect the electrode and board.
Ferroli Error Code A03: Overheating or Heating Sensor Issue
Error code A03 on your Ferroli boiler means the system has detected overheating or a problem with the temperature sensor, often because water isn’t circulating properly.
What Causes Error Code A03
Air in the system, a struggling pump, sludge build-up, or a damaged sensor can trigger it.
How to Fix
- Bleed all radiators to remove trapped air.
- Check the boiler pressure gauge and top up if needed.
- Reset the boiler and monitor.
- If the code persists, arrange a professional service to clean the system and check the pump and sensor.
Ferroli Error Code A05: Fan Fault
Error code A05 on your Ferroli boiler indicates the fan that safely removes exhaust gases isn’t working correctly or isn’t getting the right signal.
What Causes Error Code A05
A worn fan, loose wiring, or obstruction in the flue are common causes.
How to Fix
- Reset the boiler.
- Listen for fan noise when it tries to start.
- If the code stays, a Gas Safe engineer must inspect and replace the fan if needed.
Ferroli Error Code A06: No Flame After Ignition Attempt
Error code A06 on your Ferroli boiler means the burner lit briefly but then lost the flame, so the boiler shut down.
What Causes Error Code A06
Low gas pressure, a blocked condensate pipe (especially in winter), unstable flame, or a faulty flame sensor.
How to Fix
- Check gas supply and reset the boiler.
- In cold weather, thaw the condensate pipe outside with warm (not boiling) water if frozen.
- If it returns, call an engineer to check the sensor and gas settings.
Ferroli Error Code F05: Air Pressure Switch Error
Error code F05 on your Ferroli boiler shows the air pressure switch (which checks safe flue operation) isn’t reading correctly.
What Causes Error Code F05
Blocked flue, wrong baffle size, or a faulty switch are typical.
How to Fix
- Visually check the flue outlet for debris, leaves or snow.
- Reset the boiler.
- If the fault repeats, a professional must clean the flue and test the switch.
Ferroli Error Code F07: Air Pressure Switch or High Flue Temperature
Error code F07 on your Ferroli boiler points to the air pressure switch contacts closing too soon or flue gases getting too hot.
What Causes Error Code F07
Fan issues, flue blockages or restricted airflow cause this.
How to Fix
- Reset and check the flue for blockages.
- If it persists, have an engineer inspect the fan and flue system.
Ferroli Error Code A09 or A16: Gas Valve Fault
Error code A09 or A16 on your Ferroli boiler means the gas valve isn’t opening or closing properly.
What Causes Error Code A09 or A16
Wiring problems, a faulty valve, or low voltage.
How to Fix
- Reset the boiler.
- Check mains voltage if possible.
- Persistent faults need a Gas Safe engineer to test and replace the valve.
Ferroli Error Code F10: Flow Temperature Sensor Fault
Error code F10 on your Ferroli boiler indicates the sensor measuring outgoing hot water temperature isn’t working correctly.
What Causes Error Code F10
Damaged sensor, loose wiring, or short circuit.
How to Fix
- Reset the boiler.
- An engineer will test the sensor and wiring.
Ferroli Error Code F11: Hot Water Sensor Fault
Error code F11 on your Ferroli boiler shows the hot water temperature sensor is faulty.
What Causes Error Code F11
Similar to F10 – wiring issues or a failed sensor.
How to Fix
- Reset and test hot water taps.
- Professional replacement is usually needed.
Ferroli Error Code F34: Supply Voltage Too Low
Error code F34 on your Ferroli boiler means the electricity supply is below the safe level (under 170V).
What Causes Error Code F34
Mains power problems, loose wiring, or fluctuations.
How to Fix
- Check other appliances for power issues.
- If it continues, an electrician or engineer should check your supply.
Ferroli Error Code F37: Low System Water Pressure
Error code F37 on your Ferroli boiler is one of the most frequent and simply means the water pressure in your heating system is too low.
What Causes Error Code F37
Small leaks, bleeding radiators, or natural loss over time.
How to Fix
- Check the pressure gauge – it should read 1–1.5 bar when cold.
- Open the filling loop (silver hose underneath) slowly until the gauge reaches 1.2–1.5 bar.
- Close valves and reset.
- If pressure drops again, call an engineer to find the leak.
Ferroli Error Code F43: Heat Exchanger Protection Activated
Error code F43 on your Ferroli boiler means the system has detected poor water circulation and activated protection to prevent damage.
What Causes Error Code F43
Air in the system, sludge, or pump problems.
How to Fix
- Bleed all radiators.
- Check and top up pressure.
- Reset and arrange a service if it returns.
Ferroli Error Code F50 or F51: Control Board or Controller Error
Error code F50 or F51 on your Ferroli boiler indicates an internal problem with the control board.
What Causes Error Code F50 or F51
Parameter settings, electrical surges, or board failure.
How to Fix
- Reset the boiler.
- Persistent codes need an engineer to check or replace the board.
Getting your boiler serviced regularly catches sensor, fan and pressure issues early, keeping repair costs down and your system running efficiently year after year.
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If you’re due for a routine check-up, tune-up or want to prevent future issues, start with our boiler service plans.
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Frequently Asked Questions
Does the FH code on my Ferroli boiler mean something is wrong?
No – FH (or Fh) simply shows the boiler is running its automatic air-purging cycle after a reset or power cut. It’s normal and will disappear once complete.
Are Ferroli error codes different for every model?
Yes – older models like Domicompact use F1/F2 style codes while newer ones like BlueHelix use A and F codes. Always check your exact model’s manual for precise details.
Can I keep resetting a Ferroli boiler error code safely?
Only once or twice to see if it clears. Repeated resets without fixing the cause can stress parts and may void your warranty.
Will a Ferroli boiler error code always mean an expensive repair?
Not at all – many like F37 or simple sensor issues are low-cost or DIY-friendly. Early attention often prevents bigger problems.
Do landlords need to act immediately on tenant-reported Ferroli error codes?
Yes – it’s part of keeping the property safe and compliant. A quick service visit resolves most codes and avoids disruption for tenants.
