BoilerFaultCodes 4 (Flashing Light)
Your boiler is currently in standby mode and is working correctly, simply waiting for either the room thermostat or a hot tap to be turned on.
Ferroli DOMINAplus F28D Fault codes & diagnostics
26 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Combi Natural Gas 28 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. 15 High
3 Medium
8 Low
Just want the most common Ferroli DOMINAplus F28D faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes
All 26 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.
Your boiler has stopped working because the water pressure inside the heating system has dropped too low.
What to check first
- Locate the filling loop (a flexible metal hose) underneath your boiler or near your airing cupboard pipes.
- Open the valves on the filling loop to allow cold mains water to enter the system while watching the pressure gauge.
- Close the valves firmly once the needle sits between 1.0 and 1.5 bar, then restart your boiler.
Parts commonly replaced
- Filling loop
- Pressure gauge
- Pressure relief valve
LED 4 (Flashing light)
Your boiler is perfectly healthy and is simply waiting for a signal from your thermostat or hot water tap to start heating.
LED 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 (a flexible silver hose) underneath the boiler.
- Open the taps on both ends of the hose to allow water into the system.
- Monitor the pressure gauge on the front panel and close both taps once the needle reaches 1.5 bar.
Parts commonly replaced
- Filling loop
- Pressure gauge
- Pressure safety valve
Digital codes
4 (Permanent Light)
Your boiler is currently operating normally and is actively heating your radiators.
5 (Permanent Light) Your boiler is operating normally and is simply indicating that it is receiving electrical power.
Your boiler is operating normally and is simply indicating that it is receiving electrical power.
What to check first
- No action required as this is a status indicator rather than a fault code.
- Ensure your heating or hot water controls are set correctly if you are not receiving heat.
Boiler shut down (lock out) Your boiler has stopped working as a safety precaution and needs a manual reset to try and start up again.
Your boiler has stopped working as a safety precaution and needs a manual reset to try and start up again.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Printed Circuit Board (PCB)
E01 Your boiler has failed to light the flame, which means you currently have no heating or hot water until the ignition process is corrected.
Your boiler has failed to light the flame, which means you currently have no heating or hot water until the ignition process is corrected.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Control board/PCB
Related codes
E02 Your boiler has automatically turned itself off because it has become too hot to operate safely.
Your boiler has automatically turned itself off because it has become too hot to operate safely.
Parts commonly replaced
- Overheat thermostat
- Central heating pump
- System filter
Related codes
E03 Your boiler is struggling to clear exhaust gases properly, so it has safely shut itself down to prevent any risk of fumes entering your home.
Your boiler is struggling to clear exhaust gases properly, so it has safely shut itself down to prevent any risk of fumes entering your home.
Parts commonly replaced
- Air pressure switch
- Flue fan assembly
- Venturi
Showing 11–20 of 26
E04 Your boiler has stopped working because the water pressure inside the heating system has dropped too low.
Your boiler has stopped working because the water pressure inside the heating system has dropped too low.
What to check first
- Locate the filling loop, which is a silver braided hose connecting two pipes underneath the boiler.
- Open the valves at both ends of the hose to allow mains water to enter the system until the pressure gauge reads 1.5 bar.
- Close both valves tightly and remove the hose if required by your specific installation.
Parts commonly replaced
- Filling loop
- Pressure sensor
- Pressure relief valve
E05 Your boiler has stopped heating your radiators because the sensor that monitors internal water temperature is sending an incorrect or broken signal.
Your boiler has stopped heating your radiators because the sensor that monitors internal water temperature is sending an incorrect or broken signal.
Parts commonly replaced
- Central heating flow NTC sensor
- Wiring harness
Related codes
E06 Your boiler is struggling to detect the temperature of your hot water, so it has stopped heating it to prevent the system from overheating.
Your boiler is struggling to detect the temperature of your hot water, so it has stopped heating it to prevent the system from overheating.
Parts commonly replaced
- Domestic Hot Water (DHW) NTC sensor
Related codes
Heating demand light ON Your boiler is confused and thinks it is constantly being asked for heating, which usually means the temperature sensor is sending a false signal.
Your boiler is confused and thinks it is constantly being asked for heating, which usually means the temperature sensor is sending a false signal.
Parts commonly replaced
- Central Heating NTC Sensor
Insufficient pressure Your boiler has stopped working because the water pressure inside your heating system has dropped too low to operate safely.
Your boiler has stopped working because the water pressure inside your heating system has dropped too low to operate safely.
What to check first
- Locate the filling loop (a silver braided hose) underneath the boiler
- Open the small valve or tap attached to the hose slowly
- Watch the pressure gauge on the front of the boiler until the needle reaches between 1 and 1.5 bar
- Close the valve tightly to stop the flow of water
Parts commonly replaced
- Filling loop
- Pressure relief valve
- Pressure gauge
LED 4
Your boiler is currently taking a short, scheduled break to prevent the system from cycling on and off too frequently.
LED 4 (Permanent light)
Your boiler is simply indicating that the central heating system is currently active and running normally to warm your radiators.
LED 5 Your boiler has detected that the water pressure inside the system has dropped too low for it to operate safely, meaning your heating and hot water will not turn on.
Your boiler has detected that the water pressure inside the system has dropped too low for it to operate safely, meaning your heating and hot water will not turn on.
What to check first
- Locate the filling loop, which is usually a flexible silver hose with one or two small valves connecting your boiler or nearby pipework.
- Open the valve(s) slowly to allow mains water into the system until the pressure gauge on the front of the boiler reads between 1.0 and 1.5 bar.
- Close the valve(s) tightly and check that the fault light has cleared.
Parts commonly replaced
- Pressure relief valve
- Pressure sensor
- Expansion vessel
LED 5 (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)
- Power supply cable
- Main electrical fuse
Related codes
LED1 Your boiler is not detecting the stable electrical power it needs to function correctly, which is usually caused by a loose connection or an issue with your home's power supply.
Your boiler is not detecting the stable electrical power it needs to function correctly, which is usually caused by a loose connection or an issue with your home's power supply.
Parts commonly replaced
- Printed Circuit Board (PCB)
- Wiring harness
- Fuse
Showing 21–26 of 26
LED2 Your boiler is failing to light the flame properly, which has caused it to stop working as a safety precaution.
Your boiler is failing to light the flame properly, which has caused it to stop working as a safety precaution.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Main PCB
LED3
Your boiler is currently operating normally and is actively responding to a signal from your thermostat or internal timer to heat your home.
Low water pressure light ON Your boiler has stopped working because the amount of water inside your heating system has dropped below the required level.
Your boiler has stopped working because the amount of water inside your heating system has dropped below the required level.
What to check first
- Locate the external filling loop, which is a flexible braided hose connecting your central heating pipework to your mains water pipe.
- Open the small valves at both ends of this hose slowly to allow water to enter the system while watching the pressure gauge on the front of the boiler.
- Close both valves firmly once the needle sits between 1.0 and 1.5 bar.
Parts commonly replaced
- Pressure relief valve
- Pressure transducer
- Expansion vessel
Red LED Out (Lockout) Your boiler has stopped working because it cannot safely ignite the flame required to provide heating or hot water.
Your boiler has stopped working because it cannot safely ignite the flame required to provide heating or hot water.
Parts commonly replaced
- Overheat thermostat
- Ignition electrode
- Gas valve
- PCB
Red light (Egg timer symbol)
Your boiler is perfectly fine; it is merely resting for three minutes between heating cycles to prevent excessive wear and tear.
Tap symbol light ON Your boiler is struggling to detect when you turn on the hot tap, meaning you may experience issues getting hot water to your taps or shower.
Your boiler is struggling to detect when you turn on the hot tap, meaning you may experience issues getting hot water to your taps or shower.
Parts commonly replaced
- DHW NTC thermistor sensor