Ferroli Bluehelix HiTech RRT Fault codes & diagnostics

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

Combi Natural Gas 2022-present
GC Numbers 47-267-7447-267-7547-267-76
Download the Ferroli Bluehelix HiTech RRT manual The official installation & service manual (PDF) — the exact document these fault codes were verified against. PDF

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Severity at a glance

Each cell = one fault code. Hover to identify.
1 Emergency 31 High 2 Medium 2 Low
Just want the most common Ferroli Bluehelix HiTech RRT faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 36 documented codes

Tap any card for details

A01

Your boiler has failed to light, which means your heating and hot water will not work until the gas supply or ignition system is restored.

High DIY-safe £120-350

What to check first

  1. Check that your gas meter has credit and the isolation valve is open
  2. Check if other gas appliances in your home, like a hob, are working
  3. Press the 'Reset' button on the boiler control panel for 1 second

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • PCB (Control board)

Related codes

Full explanation for A01
A02

Your boiler detects a flame when it should be off, which is usually caused by a drainage issue or a sensor fault.

High Engineer only £120-350

Parts commonly replaced

  • Condensate trap
  • Ionisation electrode
  • Ignition cable
  • Printed Circuit Board (PCB)

Related codes

Full explanation for A02
A06

Your boiler is failing to keep a flame lit after it starts up, which means it cannot heat your water or radiators.

High Engineer only £120-280

Parts commonly replaced

  • Ionisation electrode
  • Gas valve
  • PCB (Control Board)

Related codes

Full explanation for A06
A07

Your boiler has detected that the exhaust gases are becoming too hot and has shut down as a safety precaution.

High Engineer only £120-350

Parts commonly replaced

  • Fume probe
  • Heat exchanger
  • Main PCB

Related codes

Full explanation for A07
A08

Your boiler has switched itself off because it has detected it is getting too hot, likely due to a lack of water flow or a sensor issue.

High DIY-safe £120-350

What to check first

  1. Check that your boiler pressure is between 1 and 1.5 bar on the display
  2. Ensure all radiator valves and the isolation valves under the boiler are fully open
  3. Try resetting the boiler by pressing the 'Reset' button for one second

Parts commonly replaced

  • Central heating pump
  • Temperature sensors (NTC)
  • Main heat exchanger (flushing/cleaning)

Related codes

Full explanation for A08
A09

Your boiler has stopped working because water isn't flowing through the main heating unit properly, causing it to overheat for protection.

High DIY-safe £120-£450

What to check first

  1. Check that your boiler pressure is between 1.0 and 1.5 bar
  2. Ensure all radiator valves and isolation valves are fully open
  3. Try resetting the boiler if the pressure is correct

Parts commonly replaced

  • Circulation pump
  • Main heat exchanger
  • System filter (cleaning/replacement)

Related codes

Full explanation for A09
A14

Your boiler has locked itself out because it has repeatedly detected a problem with how exhaust gases are being cleared from the system.

High Engineer only £120-350

Parts commonly replaced

  • Flue sensor
  • Fan assembly
  • Main PCB
  • Heat exchanger (cleaning)

Related codes

Full explanation for A14
A23

Your boiler has lost the ability to monitor the water pressure correctly, causing the system to stop working to prevent damage.

High Engineer only £140-£260

Parts commonly replaced

  • Water pressure transducer
  • Wiring harness

Related codes

Full explanation for A23
A24

Your boiler is struggling to accurately measure the water pressure inside the system, which is preventing it from heating up correctly.

High Engineer only £120-£210

Parts commonly replaced

  • Water pressure transducer
  • Wiring harness

Related codes

Full explanation for A24
A26

Your boiler has shut down because it has detected high water pressure too many times in a single day, which usually points to a system blockage or a faulty expansion tank.

High DIY-safe £120-280

What to check first

  1. Check the pressure gauge on the front of the boiler; it should be between 1 and 1.5 bar.
  2. If the pressure is too high (above 2.5 bar), bleed water from a radiator using a bleed key to lower the pressure.
  3. Ensure the filling loop valves are tightly closed and not accidentally letting water into the system.

Parts commonly replaced

  • Expansion Vessel
  • Pressure Sensor
  • Safety Relief Valve

Related codes

Full explanation for A26
Showing 11–20 of 36
A44

Your boiler is receiving too many rapid signals to turn on and off in a short period, causing it to temporarily stop for protection.

Medium DIY-safe £80-180

What to check first

  1. Check that all radiator valves (TRVs) are fully open to ensure water can flow properly.
  2. Verify that your room thermostat is not set to a temperature very close to the current room temperature.
  3. Restart the boiler using the reset button on the control panel.

Parts commonly replaced

  • External Room Thermostat
  • PCB (Control Board)
  • Diverter Valve

Related codes

Full explanation for A44
A80

Your boiler is still detecting a flame even though it has commanded the gas to turn off, which is a safety concern that prevents the unit from operating.

Emergency Engineer only £140-380

Parts commonly replaced

  • Ionisation Electrode
  • Gas Valve
  • Control Board

Related codes

Full explanation for A80
A88

Your boiler is having trouble managing its flame correctly during the starting or burning process, meaning it cannot heat your home reliably.

High Engineer only £120-350

Parts commonly replaced

  • Gas Valve
  • Electrode
  • Control Board

Related codes

Full explanation for A88
A98

Your boiler's internal computer has encountered a software glitch or a configuration error and needs to be restarted and recalibrated.

High DIY-safe £100-350

What to check first

  1. Press the Reset button on the boiler control panel
  2. Wait for the boiler to complete its automatic startup sequence
  3. If the code persists, the boiler may require a professional 'Auto Setup' calibration

Parts commonly replaced

  • Main PCB (Printed Circuit Board)
  • Display Interface

Related codes

Full explanation for A98
A99

Your boiler has detected a general problem with its breathing or fuel supply and has shut down as a safety precaution.

High Engineer only £100-250

Parts commonly replaced

  • Gas Valve
  • Condensate Trap
  • Flue Seals

Related codes

Full explanation for A99
F09

Your boiler has shut down because it is getting too hot and water is not moving through the system correctly.

High DIY-safe £120-£350

What to check first

  1. Check that your system pressure is between 1.0 and 1.5 bar on the gauge
  2. Ensure all radiator valves are fully open to allow water flow
  3. Try resetting the boiler using the 'R' button once the unit has cooled down

Parts commonly replaced

  • Return temperature sensor (NTC)
  • Circulation pump
  • Main heat exchanger (flushing/cleaning)

Related codes

Full explanation for F09
F10

Your boiler's temperature sensor is unable to read the water flow, preventing it from heating up safely.

High Engineer only £90-180

Parts commonly replaced

  • NTC Flow Sensor
  • Wiring Loom

Related codes

Full explanation for F10
F11

Your boiler has stopped working because it cannot accurately measure the temperature of the water coming back into the unit from your radiators.

High Engineer only £90-160

Parts commonly replaced

  • Return temperature sensor (NTC thermistor)
  • Sensor wiring harness

Related codes

Full explanation for F11
F12

Your boiler is unable to provide hot water because the internal sensor responsible for monitoring water temperature has failed or lost its electrical connection.

Medium Engineer only £90-160

Parts commonly replaced

  • DHW Temperature Sensor (NTC)
  • Sensor Wiring Harness

Related codes

Full explanation for F12
F13

Your boiler has detected an issue with the sensor that monitors exhaust gases, preventing the unit from running safely.

High Engineer only £120-220

Parts commonly replaced

  • Fume temperature probe
  • Wiring harness

Related codes

Full explanation for F13
Showing 21–30 of 36
F15

Your boiler has shut down because the exhaust gases have become too hot, which is usually caused by a lack of water flow or a build-up of limescale inside the heat exchanger.

High Engineer only £150-£450

Parts commonly replaced

  • Main Heat Exchanger
  • Flue NTC Sensor
  • Circulation Pump

Related codes

Full explanation for F15
F19

Your boiler's internal computer has lost its correct configuration settings and needs to be reprogrammed to recognise the system properly.

High Engineer only £80-160

Parts commonly replaced

  • Main PCB (Control Board)

Related codes

Full explanation for F19
F21

Your boiler has detected that there is a bit too much water pressure in the system, which may cause it to stop working for safety.

Low DIY-safe £60-120

What to check first

  1. Locate a radiator bleed valve and use a radiator key to release a small amount of water into a cloth or bowl.
  2. Monitor the pressure gauge on the boiler front or display until it drops to between 1.0 and 1.5 bar.
  3. Restart the boiler to see if the fault code clears.

Parts commonly replaced

  • Filling loop valve
  • Pressure sensor
  • Expansion vessel

Related codes

Full explanation for F21
F34

Your boiler has detected that the electricity supply from the mains is too weak for it to operate safely.

High Engineer only £100-350

Parts commonly replaced

  • PCB (Main Control Board)
  • Voltage Regulator

Related codes

Full explanation for F34
F35

Your boiler has detected an issue with the electrical power coming from your home’s mains supply, meaning the electricity frequency is not compatible with the unit.

High Engineer only £100-350

Parts commonly replaced

  • PCB (Main Control Board)
  • Voltage Stabiliser

Related codes

Full explanation for F35
F37

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

High DIY-safe £0-160

What to check first

  1. Locate the filling loop (usually a silver flexible hose) underneath the boiler.
  2. Slowly open the small tap(s) on the loop until you hear water entering the system.
  3. Watch the pressure gauge or display until it reaches between 1.0 and 1.5 bar, then close the tap(s) tightly.

Parts commonly replaced

  • Water pressure transducer
  • Filling loop valve
  • Expansion vessel

Related codes

Full explanation for F37
F39

Your boiler has lost connection with its outdoor temperature sensor, which helps it decide how hard to work based on the weather outside.

Low Engineer only £90-160

Parts commonly replaced

  • External temperature probe
  • Wiring harness

Related codes

Full explanation for F39
F40

Your boiler’s internal water pressure has reached a limit that is too high, or a part that handles pressure changes has failed.

High DIY-safe £120-280

What to check first

  1. Check the pressure gauge to see if it is in the red zone (above 2.5 or 3 bar)
  2. Locate a radiator bleed valve and use a key to release a small amount of water into a cloth to lower the pressure
  3. Ensure the filling loop valves are fully closed and not accidentally letting more water into the system

Parts commonly replaced

  • Expansion Vessel
  • Pressure Sensor
  • Safety Relief Valve

Related codes

Full explanation for F40
F47

Your boiler has lost communication with the internal sensor that monitors water pressure, meaning it cannot confirm if it is safe to fire up.

High Engineer only £130-£240

Parts commonly replaced

  • Water pressure transducer
  • Wiring harness
  • Electronic Control Board (PCB)

Related codes

Full explanation for F47
F50

Your boiler has shut down because a safety sensor has detected that it is overheating or has a communication error with its safety controls.

High Engineer only £120-220

Parts commonly replaced

  • Limit Thermostat
  • Control PCB
  • Overheat Sensor

Related codes

Full explanation for F50
Showing 31–36 of 36
F51

Your boiler has shut down because a temperature safety sensor has detected a potential overheating issue or has developed a fault itself.

High Engineer only £120-220

Parts commonly replaced

  • Limit Thermostat
  • Overheat Sensor (NTC)
  • Wiring Harness

Related codes

Full explanation for F51
F62

Your boiler’s internal computer system has been replaced or reset and simply needs to be programmed to recognize the correct settings for your heating system.

High Engineer only £90-180

Parts commonly replaced

  • PCB (Printed Circuit Board)
  • Ignition Electrode

Related codes

Full explanation for F62
F64

Your boiler has been manually reset too many times in a short period and has temporarily locked itself for safety reasons.

High DIY-safe £0-120

What to check first

  1. Locate the boiler power switch or plug nearby.
  2. Turn the power off completely for at least 60 seconds.
  3. Turn the power back on and wait for the boiler to restart.

Parts commonly replaced

  • None (Software lock)
  • Ignition Electrode
  • Gas Valve

Related codes

Full explanation for F64
F65

Your boiler's electronic control system is struggling to manage the burner's flame correctly, causing the unit to shut down for safety.

High Engineer only £140-350

Parts commonly replaced

  • Main PCB
  • Electrodes
  • Gas Valve

Related codes

Full explanation for F65
F96

Your boiler is struggling to keep the flame lit after it starts up, causing the system to shut down for safety.

High Engineer only £120-350

Parts commonly replaced

  • Ionisation electrode
  • Gas valve
  • Burner gasket

Related codes

Full explanation for F96
F99

Your boiler's internal computer and the front display screen are unable to talk to each other, preventing the boiler from receiving instructions.

High Engineer only £120-350

Parts commonly replaced

  • Communication cable
  • Display PCB
  • Main control board

Related codes

Full explanation for F99
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