BoilerFaultCodes 4 (Flashing Light)
Your boiler is currently idle and is simply waiting for a signal to provide heating or hot water, so there is no fault with the unit.
Ferroli F24 Fault codes & diagnostics
10 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Combi Natural Gas 24 kW Discontinued
This boiler uses LED flash patterns
Count the flashes in one repeating group before the pause. That number is your fault code. Do not reset until you have noted it. How to read fault codes →
Severity at a glance
Each cell = one fault code. Hover to identify. 5 High
5 Low
Just want the most common Ferroli F24 faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes
All 10 documented codes
Tap any card for details
LED / flash-pattern codes
5 (Flashing Light) Your boiler has stopped working because the water pressure inside the heating system has dropped too low to operate safely.
Your boiler has stopped working because the water pressure inside the heating system has dropped too low to operate safely.
What to check first
- Locate the external filling loop, which is usually a small metal braided hose with one or two valves located underneath the boiler.
- Open the valve(s) slowly to allow water into the system while watching the pressure gauge on the front of the boiler.
- Close the valve(s) tightly once the needle on the gauge reaches the green zone, typically between 1.0 and 1.5 bar.
Parts commonly replaced
- Filling loop
- Pressure relief valve
- Pressure sensor
LED 4 (Flashing light)
Your boiler is currently in standby mode and is simply waiting for a demand for heating or hot water, so there is no fault at all.
LED 5 bar (Flashing light) Your boiler has detected that there is not enough water inside your heating system to run safely and correctly.
Your boiler has detected that there is not enough water inside your heating system to run safely and correctly.
What to check first
- Locate the external filling loop (a flexible metal or braided pipe) underneath your boiler.
- Open the small valve handle on the filling loop to allow cold water into the system until the pressure gauge reads between 1.0 and 1.5 bar.
- Close the valve tightly to prevent over-pressurisation.
Parts commonly replaced
- Pressure relief valve
- Expansion vessel
- Pressure sensor
Digital codes
4 (Permanent Light)
Your boiler is currently operating normally to heat your radiators.
5 (Permanent Light)
Your boiler is operating normally and is receiving mains electricity as expected.
LED 2 Your boiler has detected an internal failure or lack of ignition, which has caused it to automatically stop working to ensure your safety.
Your boiler has detected an internal failure or lack of ignition, which has caused it to automatically stop working to ensure your safety.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Printed Circuit Board (PCB)
LED 4 (Permanent light)
Your boiler is currently operating normally and successfully providing heat to your radiators.
LED 5 bar (Permanent light) Your boiler is failing to detect a stable electrical supply, which is preventing it from starting up or operating correctly.
Your boiler is failing to detect a stable electrical supply, which is preventing it from starting up or operating correctly.
Parts commonly replaced
- Printed Circuit Board (PCB)
- Wiring harness
- Power supply fuse
Red lockout light Your boiler has stopped working for safety reasons and needs a manual reset or a professional check to get your heating and hot water back on.
Your boiler has stopped working for safety reasons and needs a manual reset or a professional check to get your heating and hot water back on.
Parts commonly replaced
- Ignition electrode
- Flame sensor
- Gas valve
- PCB