Ferroli Falcon Fault codes & diagnostics

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

Combi Natural Gas 24-30 kW 2007-2012 Discontinued
GC Number 47-267-01

Replaced by: Ferroli Modena

Download the Ferroli Falcon manual The official installation & service manual (PDF) — the exact document these fault codes were verified against. PDF

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.
13 High 1 Medium 2 Low
Just want the most common Ferroli Falcon faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 16 documented codes

Tap any card for details

LED / flash-pattern codes
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 filling loop (a flexible silver hose) underneath the boiler.
  2. Open the small valve(s) on the loop to allow water into the system.
  3. Monitor the pressure gauge on the boiler until it reaches the green zone (typically 1.0 to 1.5 bar).
  4. Close the valve(s) tightly to stop the flow.

Parts commonly replaced

  • Pressure relief valve
  • Filling loop
Full explanation for 5 (Flashing)
LED 5 Flashing

Your boiler's electronic control centre is failing to communicate properly, which has caused the system to shut down for safety.

High Engineer only £250-450

Parts commonly replaced

  • Main printed circuit board (PCB)
  • 2A internal fuse
  • Wiring loom
Full explanation for LED 5 Flashing
LED4 flashing

Your boiler is struggling to detect water moving through the system, which prevents it from safely firing up to heat your home or provide hot water.

High Engineer only £150-300

Parts commonly replaced

  • Flow sensor
  • Circulation pump
  • PCB main board
Full explanation for LED4 flashing
LED5 (Flashing)

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

High DIY-safe £80-120

What to check first

  1. Locate the filling loop, which is a silver braided hose with one or two valves connecting your boiler to the mains water supply.
  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. Turn off the valve(s) completely and ensure they are tightened to prevent future pressure loss.

Parts commonly replaced

  • Filling loop
  • Pressure relief valve
  • Pressure sensor
Full explanation for LED5 (Flashing)
Digital codes
Boiler lock out

Your boiler has stopped working as a safety precaution and needs to be manually reset to try and restart the system.

High DIY-safe £100-250

What to check first

  1. Locate the on/off/reset switch on the front control panel.
  2. Turn the switch to the 'reset' position and hold it briefly.
  3. Return the switch to the 'on' position and wait to see if the burner ignites.

Parts commonly replaced

  • Ignition electrode
  • Flame rectification probe
  • Printed circuit board (PCB)
Full explanation for Boiler lock out
Bottom red light

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

High DIY-safe £80-120

What to check first

  1. Locate the filling loop, which is usually a flexible silver hose or two valves sitting underneath the boiler.
  2. Open the valves slowly to allow water into the system until the pressure gauge needle reaches the 1 to 1.5 bar mark.
  3. Close both valves tightly to stop the flow of water and check if the red light resets.

Parts commonly replaced

  • Filling loop
  • Pressure gauge
  • Pressure relief valve
Full explanation for Bottom red light
Heating demand light ON

Your boiler is confused because a sensor that measures the temperature of your heating water has stopped sending the correct signal, so it has turned off the heating to stay safe.

High Engineer only £120-200

Parts commonly replaced

  • Central Heating NTC Sensor
  • Wiring harness
Full explanation for Heating demand light ON
LED 3 OFF (DHW Mode)

Your boiler has lost the ability to measure the temperature of the water used for your taps and shower, so it cannot produce hot water.

High Engineer only £120-200

Parts commonly replaced

  • DHW NTC sensor
  • Wiring harness
Full explanation for LED 3 OFF (DHW Mode)
LED 5 ON

Your boiler has stopped working because the water pressure inside the 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 hose with one or two valves connecting your boiler to the mains water supply.
  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 and 1.5 bar.
  3. Fully close the valve(s) and ensure no water is dripping from the connection.

Parts commonly replaced

  • Filling loop
  • Pressure gauge
Full explanation for LED 5 ON
LED2

Your boiler has detected a safety concern or overheating issue and has intentionally shut itself down to prevent damage.

High Engineer only £120-£250

Parts commonly replaced

  • Safety limit thermostat
  • Overheat sensor
  • Printed Circuit Board (PCB)

Related codes

Full explanation for LED2
Low water pressure light ON

Your boiler has stopped working because the water pressure inside the system has dropped too low, which is causing it to lock itself to prevent damage.

High DIY-safe £80-150

What to check first

  1. Locate the filling loop (a silver flexi-hose) underneath your boiler.
  2. Open the valves attached to the loop until you hear water flowing.
  3. Watch the pressure gauge on the front of the boiler until the needle reaches between 1 and 1.5 bar.
  4. Firmly close the valves to stop the flow.

Parts commonly replaced

  • Pressure relief valve
  • Pressure sensor switch
  • Expansion vessel
Full explanation for Low water pressure light ON
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
  • Flame sensor
  • Printed Circuit Board (PCB)
  • Gas valve
Full explanation for Red lockout light
Tap symbol light ON

Your boiler is struggling to detect the temperature of the water for your taps, which means it will likely stop providing hot water until the faulty sensor is replaced.

Medium Engineer only £100-200

Parts commonly replaced

  • DHW NTC thermistor
  • Wiring harness
Full explanation for Tap symbol light ON
Status & diagnostic codes

8 operating states & engineer diagnostics

Not faults — these are normal operating states. Tap to expand.

4 (Flashing) Status Your boiler is currently in standby mode and is working exactly as it should while waiting for a request for heat. LED4 (Flashing) Status Your boiler is currently in standby mode and is working exactly as it should, waiting for a signal to provide heat or hot water. Heating demand light OFF Status Your boiler is currently idle because it is not receiving a signal from your thermostat or timer to turn the heating on. LED1 Diagnostic Your boiler has failed to ignite, meaning it is currently unable to produce heat or hot water because it cannot successfully light its internal burner. LED3 Status Your boiler is operating normally and is currently receiving instructions from your thermostat or timer to provide heating. LED4 (Permanent) Status Your boiler is correctly operating in heating mode, and the light indicates that your central heating system is currently active. LED5 (Permanent) Status Your boiler is failing to detect the incoming electrical power required to operate safely. Tap symbol light OFF Status Your boiler is failing to detect that you have turned on a hot tap, so it is not firing up to heat your water.