Ferroli Domina 102 Fault codes & diagnostics

36 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.

Combi Natural Gas 24 kW 2000-2005 Discontinued

Replaced by: Domina F 24 E

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.
23 High 1 Medium 12 Low

All 36 documented codes

Tap any card for details

4 (Flashing Light)

Your boiler is currently idle and waiting for a signal to provide heating or hot water, so it is simply in 'standby' mode and functioning as expected.

Low DIY-safe

What to check first

  1. Check your room thermostat is set to a higher temperature than the current room temperature
  2. Ensure your heating programmer or timer is set to the 'on' position
  3. Check that the hot water tap is turned on if you are testing for hot water demand
5 (Flashing Light)

Your boiler has stopped working because the water pressure inside the heating system has dropped too low.

High DIY-safe £0-£100

What to check first

  1. Locate the filling loop, which is a flexible silver pipe with one or two small valves connecting your cold water supply to the boiler.
  2. Open the valve(s) slowly to allow water into the system until the pressure gauge on the front of the boiler reads between 1.0 and 1.5 bar.
  3. Close the valve(s) tightly and check that the fault light has cleared.

Parts commonly replaced

  • Filling loop
  • Pressure gauge
  • Expansion vessel
5 (Flashing)

Your boiler has stopped working because the water pressure inside the heating system has dropped too low to operate safely.

High DIY-safe £80-120

What to check first

  1. Locate the external filling loop, which is usually a braided silver hose connecting two pipes under the boiler
  2. Open the small valve or tap on the filling loop to allow cold mains water to enter the system
  3. Watch the pressure gauge on the front of the boiler and close the valve once the needle reaches 1.5 bar
  4. Check for any obvious puddles under radiators or the boiler that might explain the initial pressure loss

Parts commonly replaced

  • Filling loop
  • Pressure relief valve
  • Pressure gauge
LED 5 (Flashing light)

Your boiler has stopped working because the water pressure inside the heating system has dropped too low to operate safely.

High DIY-safe £0-90

What to check first

  1. Locate the external filling loop (a flexible silver hose connecting two pipes near the boiler).
  2. Slowly open the tap or valve on the filling loop to allow water into the system.
  3. Watch the pressure gauge on the boiler until the needle reaches the green zone (usually 1.0 to 1.5 bar), then close the valve tightly.

Parts commonly replaced

  • Filling loop
  • Pressure relief valve
  • Pressure gauge
LED4 (Flashing)

Your boiler is struggling to detect water flow or communicate internally, which is preventing it from starting up your heating or hot water.

High Engineer only £150-300

Parts commonly replaced

  • Flow sensor
  • PCB (Main control board)
  • Circulation pump
LED5 bar (Flashing)

Your boiler has stopped heating because the water pressure inside the system has dropped too low to operate safely.

High DIY-safe £80-150

What to check first

  1. Locate the external filling loop, which is a silver braided hose connected between two valves underneath the boiler.
  2. Open the valves slowly to allow mains cold water into the system while watching the pressure gauge.
  3. Close the valves tightly once the needle reaches the green zone, typically between 1.0 and 1.5 bar.

Parts commonly replaced

  • Filling loop
  • Pressure relief valve
  • Pressure gauge
4 (Permanent)

Your boiler is struggling to process a request for heating, meaning it cannot currently warm your home or provide hot water.

High Engineer only £120-250

Parts commonly replaced

  • Flow Switch
  • PCB Control Board
  • NTC Sensor
Showing 11–20 of 36
5 (Permanent)

Your boiler is currently receiving electricity and is operating in its normal standby or active state.

Low DIY-safe

What to check first

  1. Check your thermostat settings to ensure calling for heat
  2. Ensure hot water taps are fully closed
  3. If the boiler is running normally, no action is required as this simply indicates power flow
Boiler shut down (lock out)

Your boiler has detected a problem and safely switched itself off to prevent damage.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Flame sensor
  • Gas valve
  • PCB
E01

Your boiler is failing to light the burner, meaning it cannot produce heat or hot water because it isn't detecting a flame.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Flame rectification probe
  • Printed Circuit Board (PCB)
  • Gas valve

Related codes

E02

Your boiler has detected that it is getting too hot and has automatically switched itself off to prevent any damage.

High Engineer only £120-250

Parts commonly replaced

  • Overheat thermostat
  • Central heating pump
  • System filter
E03

Your boiler has stopped working because it cannot safely clear its exhaust gases, preventing it from lighting to keep your home safe.

High Engineer only £120-250

Parts commonly replaced

  • Air pressure switch
  • Flue fan assembly
  • Venture pipe
E04

Your boiler has stopped working because it does not have enough water inside the system to operate safely.

High DIY-safe £80-150

What to check first

  1. Locate the filling loop (a silver flexi-hose) beneath the boiler.
  2. Open the small valve handles to allow water to enter the system until the pressure gauge reads between 1 and 1.5 bar.
  3. Close the valves tightly to stop the flow of water.

Parts commonly replaced

  • Pressure relief valve
  • Pressure transducer
  • Expansion vessel
E05

Your boiler is struggling to accurately measure the temperature of the water being sent to your radiators, so it has turned itself off to avoid overheating.

High Engineer only £120-220

Parts commonly replaced

  • Central heating temperature sensor (NTC)
  • Wiring harness

Related codes

E06

Your boiler is currently unable to detect the temperature of the water coming from your taps, which means it has stopped providing hot water to prevent overheating.

High Engineer only £120-200

Parts commonly replaced

  • Domestic Hot Water (DHW) NTC temperature sensor

Related codes

E37

Your boiler has stopped heating because the water pressure inside the system has dropped below the required level.

High DIY-safe £0-£100

What to check first

  1. Locate the filling loop, which is a silver braided hose with one or two valves located underneath the boiler.
  2. Slowly open the valves to allow mains water into the heating system while watching the pressure gauge on the front of the boiler.
  3. Close the valves tightly once the needle reaches 1.5 bar, then check the boiler to see if the fault code has cleared.

Parts commonly replaced

  • Filling loop
  • Pressure relief valve
  • Pressure sensor
Showing 21–30 of 36
Heating demand light ON

Your boiler is struggling to register that you have turned the heating on, causing it to stay idle or fail to start.

Medium Engineer only £120-200

Parts commonly replaced

  • Central Heating NTC Sensor
Insufficient pressure

Your boiler has stopped working because the water pressure inside the heating system has dropped too low to operate safely.

High DIY-safe £80-120

What to check first

  1. Locate the external filling loop, which is a silver braided flexible hose connected between two pipes underneath the boiler.
  2. Open the small valve(s) on either end of the hose to allow mains water into the system until the pressure gauge reads between 1 and 1.5 bar.
  3. Firmly close the valve(s) to stop the water flow and ensure the boiler resets itself.

Parts commonly replaced

  • Filling loop
  • Pressure relief valve
  • Pressure gauge
LED 5

Your boiler has detected that there is not enough water inside the system to operate safely, so it has turned itself off to prevent damage.

High DIY-safe £80-150

What to check first

  1. Locate the external filling loop, which is usually a silver flexible hose with one or two small valves under the boiler.
  2. Open the valve(s) slowly to allow water into the system while watching the pressure gauge on the front of the boiler.
  3. Close the valve(s) tightly once the needle reaches the green zone, typically between 1 and 1.5 bar.

Parts commonly replaced

  • Pressure relief valve
  • Pressure sensor
LED 5 (Permanent light)

Your boiler is not receiving the electrical power it needs to turn on, which is usually caused by a tripped switch or a power supply issue.

High DIY-safe £90-250

What to check first

  1. Check your home's fuse box or consumer unit to see if the boiler's circuit breaker has tripped.
  2. Ensure the fused spur switch located near the boiler is turned on.
  3. Verify that the plug or connection to the wall socket is secure and hasn't vibrated loose.

Parts commonly replaced

  • Main circuit board (PCB)
  • External fuse
  • Wiring loom
LED1

Your boiler is failing to detect a stable power supply, which is preventing it from starting up or operating correctly.

High Engineer only £120-250

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Power wiring harness
  • External spur switch
LED2

Your boiler is attempting to start but failing to ignite, causing it to lock itself down for safety reasons.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • PCB
Showing 31–36 of 36
LED5 (Permanent)

Your boiler is confirming that it has a stable electrical power supply and is ready to operate under normal conditions.

Low DIY-safe £120-250

What to check first

  1. This is a status indicator rather than a fault, meaning your boiler is correctly powered.
  2. If the boiler is not working, check that your external heating controls like the timer or thermostat are calling for heat.
  3. Ensure your gas supply tap is turned on and your external fuse spur is switched on.

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Power cable/fused spur connection

Related codes

Low water pressure light ON

Your boiler has stopped working because the water pressure inside the system is too low to operate safely.

High DIY-safe £80-150

What to check first

  1. Locate the filling loop, which is a silver braided hose with one or two valves underneath the boiler.
  2. Slowly open the valve(s) to let water into the system while watching the pressure gauge on the front of the boiler.
  3. Close the valve(s) firmly once the needle sits between 1 and 1.5 bar, then check for any leaks.

Parts commonly replaced

  • Pressure relief valve
  • Pressure gauge
  • Water pressure switch
Red LED Out (Lockout)

Your boiler has stopped working for safety reasons and is refusing to ignite, which means it currently cannot provide any heating or hot water.

High Engineer only £120-250

Parts commonly replaced

  • Overheat thermostat
  • Gas valve
  • Ignition electrode
Red lockout light

Your boiler has detected a problem and safely shut itself down to prevent damage, meaning you currently have no heating or hot water.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • Flame rectification probe
  • PCB
Tap symbol light ON

Your boiler is struggling to detect the temperature of your hot water, which likely means you have no hot water working at your taps.

High Engineer only £120-180

Parts commonly replaced

  • DHW NTC sensor