Glow-worm Easicom 24 Fault codes & diagnostics

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

Combi Natural Gas 24 kW 2012 onwards Discontinued
GC Number 47-019-18

Replaced by: Easicom2

Download the Glow-worm Easicom 24 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.
33 High

Which version do you have?

The GC number on your boiler's data badge identifies the exact appliance and production years, as recorded in the UK Product Characteristics Database.

GC number Appliance (register name) Produced
47-019-18 Easicom 24 2012–present

All 33 documented codes

Tap any card for details

Err

Your boiler's control panel has developed a fault and can no longer communicate with the internal system, meaning you cannot change settings or operate the unit.

High Engineer only £180-£320

Parts commonly replaced

  • User Interface Board
  • Main PCB (Printed Circuit Board)
  • Display Ribbon Cable

Related codes

F00

Your boiler has stopped working because it can no longer accurately measure the temperature of the water heading to your radiators.

High Engineer only £90-160

Parts commonly replaced

  • Flow NTC Temperature Sensor
  • Wiring harness

Related codes

F01

Your boiler has detected a problem with the internal sensor that monitors the temperature of the water returning from your radiators, preventing it from heating correctly.

High Engineer only £90-160

Parts commonly replaced

  • Return NTC thermistor
  • Wiring harness
  • Main PCB

Related codes

F10

Your boiler has stopped working because it cannot correctly measure the temperature of the water used for your heating.

High Engineer only £90-160

Parts commonly replaced

  • Flow NTC Temperature Sensor
  • Sensor Wiring Harness

Related codes

F11

Your boiler has detected a technical fault with the sensor that monitors water returning from your radiators, preventing it from heating your home safely.

High Engineer only £90-160

Parts commonly replaced

  • Return heating NTC sensor
  • Wiring harness

Related codes

F20

Your boiler has shut down because it has reached an unsafe temperature and is trying to protect itself from damage.

High DIY-safe £120-£350

What to check first

  1. Check that the radiator valves are turned on and not blocked by furniture.
  2. Ensure the large isolation valves underneath the boiler are in the open position.
  3. Try resetting the boiler by pressing the 'Reset' button (flaming cross symbol).

Parts commonly replaced

  • Circulation Pump
  • Overheat Thermostat
  • Main Heat Exchanger (if blocked)

Related codes

F22

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

High DIY-safe £0-120

What to check first

  1. Locate the filling loop (usually a silver flexible hose) underneath your boiler.
  2. Slowly open the tap or taps on the filling loop until you hear water entering the system.
  3. Watch the pressure gauge and close the taps once the needle reaches between 1.0 and 1.5 bar.

Parts commonly replaced

  • Filling loop
  • Expansion vessel
  • Pressure sensor

Related codes

F23

Your boiler has shut down because water isn't moving through the system quickly enough, causing a large temperature gap between the outgoing and incoming pipes.

High DIY-safe £150-350

What to check first

  1. Check that all radiator valves are fully open.
  2. Ensure there is enough pressure in the system by checking the gauge is between 1 and 1.5 bar.
  3. Gently bleed your radiators to remove any trapped air that might be blocking circulation.

Parts commonly replaced

  • Circulation pump
  • Thermistor (NTC sensor)
  • Central heating filter

Related codes

F24

Your boiler is overheating because the water isn't moving through the system quickly enough.

High DIY-safe £180-350

What to check first

  1. Check that the isolation valves underneath the boiler are in the open position (the handles should be parallel to the pipes).
  2. Ensure your radiator valves are turned on and not blocked by furniture.
  3. Check if the boiler pressure gauge is between 1 and 1.5 bar.

Parts commonly replaced

  • Circulation pump
  • Pump cable
  • Main heat exchanger (if blocked)

Related codes

F26

Your boiler has detected a problem with how it controls its fuel supply, meaning it cannot safely stay lit.

High Engineer only £180-350

Parts commonly replaced

  • Gas valve
  • Main PCB
  • Wiring harness

Related codes

Showing 11–20 of 33
F27

Your boiler has sensed a flame when there shouldn't be one, or has detected a flickering signal that suggests the internal electronics are confused.

High Engineer only £120-350

Parts commonly replaced

  • Flame sensing electrode
  • Ignition lead
  • Main printed circuit board (PCB)

Related codes

F28

Your boiler is not receiving enough gas or cannot create a flame to start the heating process.

High DIY-safe £100-£350

What to check first

  1. Check if your gas prepay meter has credit
  2. Ensure your main gas stopcock is turned to the 'on' position
  3. Check if other gas appliances, like a hob, are working correctly
  4. Press the reset button (flame symbol with a cross) for five seconds

Parts commonly replaced

  • Gas valve
  • Ignition electrode
  • Spark lead
  • Printed Circuit Board (PCB)

Related codes

F29

Your boiler was working but the flame has unexpectedly gone out, causing the system to stop for safety.

High DIY-safe £100-£350

What to check first

  1. Check if other gas appliances in your home, like a hob, are working to confirm gas supply.
  2. If it is freezing outside, check if the white plastic condensate pipe leading outdoors is frozen and thaw it with warm water.
  3. Press the reset button (flame symbol with a cross) for five seconds to restart the boiler.

Parts commonly replaced

  • Ignition Electrode
  • Gas Valve
  • Spark Generator

Related codes

F32

Your boiler has detected an issue with the fan or the way air is moving through the system, preventing it from lighting safely.

High Engineer only £180-450

Parts commonly replaced

  • Fan assembly
  • Printed Circuit Board (PCB)
  • Air pressure switch

Related codes

F49

Your boiler has lost communication with your thermostat or external controls because of a possible electrical wiring issue.

High DIY-safe £80-180

What to check first

  1. Check if any wireless receiver boxes are plugged in and have power
  2. Inspect the thermostat for low batteries and replace them if necessary
  3. Turn the boiler power off and back on at the fused spur to see if the connection resets

Parts commonly replaced

  • External thermostat/programmer
  • EBUS wiring
  • PCB (Main Circuit Board)

Related codes

F61

Your boiler has detected a communication error between its internal electronics and the gas supply, preventng it from firing up safely.

High Engineer only £250-£450

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Gas Valve
  • Wiring Harness

Related codes

F62

Your boiler has detected that the gas valve is not closing properly or there is a ghost flame, which is a safety issue that stops the boiler from running.

High Engineer only £220-£450

Parts commonly replaced

  • Gas Valve
  • Printed Circuit Board (PCB)

Related codes

F63

Your boiler's internal computer has developed a memory error, preventing it from processing instructions or running safely.

High Engineer only £250-450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)

Related codes

F64

Your boiler's internal computer has encountered a serious internal error and can no longer control the system, meaning your heating and hot water will not work.

High Engineer only £250-450

Parts commonly replaced

  • Main Printed Circuit Board (PCB)

Related codes

F65

Your boiler's internal computer has reached an unsafe temperature and has shut down to prevent damage to the electronics.

High Engineer only £200-£350

Parts commonly replaced

  • Main Printed Circuit Board (PCB)
  • Internal Wiring Harness

Related codes

Showing 21–30 of 33
F67

Your boiler's internal computer is receiving a confusing signal from the flame and has shut down as a safety precaution.

High Engineer only £280-450

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Ignition Electrode

Related codes

F68

Your boiler is struggling to keep a steady flame lit, often leading it to cut out for safety.

High Engineer only £120-£250

Parts commonly replaced

  • Ionisation electrode
  • Flame sensor
  • Gas valve
  • Detection lead

Related codes

F70

Your boiler's internal computer brain and display screen are struggling to talk to each other because they don't recognise each other's security settings.

High Engineer only £100-350

Parts commonly replaced

  • Main Printed Circuit Board
  • User Interface Panel

Related codes

F71

Your boiler has detected that a temperature sensor has either come loose or stopped working correctly, meaning it can no longer safely monitor the heat of the water leaving the unit.

High Engineer only £90-160

Parts commonly replaced

  • Flow NTC thermistor
  • NTC sensor retaining clip
  • Wiring harness

Related codes

F72

Your boiler has detected that its temperature sensors are giving inconsistent readings, suggesting they are either faulty or out of sync.

High Engineer only £100-£180

Parts commonly replaced

  • Flow NTC sensor
  • Return NTC sensor
  • Primary Heat Exchanger (if blocked)

Related codes

F73

Your boiler is struggling to read its own internal water pressure, which means it has shut down as a safety precaution.

High Engineer only £140-£220

Parts commonly replaced

  • Water pressure sensor
  • Wiring harness

Related codes

F74

Your boiler's internal sensor is struggling to accurately measure the water pressure, causing the system to shut down as a safety precaution.

High Engineer only £120-£200

Parts commonly replaced

  • Water pressure sensor
  • Wiring harness

Related codes

F76

Your boiler has safety-tripped because a critical fuse designed to prevent the main heat exchanger from overheating has blown or become disconnected.

High Engineer only £180-450

Parts commonly replaced

  • Primary Heat Exchanger
  • Thermal Fuse Kit
  • Main Heat Exchanger NTC Sensor

Related codes

F77

Your boiler has detected a communication problem with the internal gas control system or the water drainage pump, causing the unit to shut down for safety.

High Engineer only £180-350

Parts commonly replaced

  • Gas valve
  • Condensate pump
  • Wiring harness

Related codes

F83

Your boiler has detected that the internal water pump is not communicating properly, which prevents it from circulating heat to your radiators and taps.

High Engineer only £150-250

Parts commonly replaced

  • Pump wiring harness
  • Printed Circuit Board (PCB)
  • Circulation pump

Related codes

Showing 31–33 of 33
F84

Your boiler has stopped working because its internal sensors are reporting conflicting temperature readings as if they have been swapped or disconnected.

High Engineer only £100-220

Parts commonly replaced

  • Flow temperature sensor
  • Return temperature sensor
  • Wiring harness

Related codes

F85

Your boiler has sensed that its tempature monitors are not correctly tracking the water flow, preventing it from heating up safely.

High Engineer only £90-180

Parts commonly replaced

  • Flow NTC sensor
  • Return NTC sensor
  • Wiring harness

Related codes

F86

Your boiler has detected an issue with the safety sensor or connection for your underfloor heating system, causing it to shut down to prevent damage.

High Engineer only £90-180

Parts commonly replaced

  • Overheat thermostat
  • External floor sensor
  • Wiring harness

Related codes

59 operating states & engineer diagnostics

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

d.00 Diagnostic This code is simply an information status indicating that your boiler is currently running at its maximum heating output to warm your home. d.01 Diagnostic Your boiler is currently just finishing its normal cooling cycle after providing heating and will return to standby shortly. d.08 Diagnostic Your boiler is currently waiting for a signal from your room thermostat to tell it to turn on the heating. d.09 Diagnostic Your boiler is receiving a standard signal from your thermostat or smart heating controller to adjust its temperature, which is a normal part of its operation. d.10 Diagnostic Your boiler is having trouble circulating water around your radiators, meaning your heating may not be working as it should. d.16 Diagnostic Your boiler is simply reporting that it is currently receiving a signal from your thermostat, which is normal operation rather than a system fault. d.17 Diagnostic Your boiler has detected that the water inside the system is not circulating or heating correctly, which usually suggests a problem with the way it senses the temperature or moves water around. d.20 Diagnostic Your boiler is simply indicating that your hot water temperature has been set to its maximum limit, and it is performing exactly as requested. d.22 Diagnostic Your boiler is simply letting you know that it is currently heating your hot water because a tap or shower is running. d.23 Diagnostic Your boiler is currently operating normally in central heating mode and this code is simply informing you that the heating system is active. d.33 Diagnostic Your boiler is struggling to get the internal fan spinning at the correct speed, which prevents the unit from starting safely. d.34 Diagnostic Your boiler has detected that the internal fan responsible for venting exhaust gases is not spinning at the correct speed, so it has shut down to keep you safe. d.36 Diagnostic Your boiler is struggling to detect the flow of water through the system, which means it cannot tell when you have turned on a hot tap. d.40 Diagnostic Your boiler is correctly reporting the current temperature of the water flowing into your heating system, and this code is simply providing information rather than indicating a failure. d.41 Diagnostic Your boiler is struggling to accurately detect the temperature of the water returning from your radiators, which may cause your heating to work inefficiently or cut out. d.43 Diagnostic Your boiler is notifying you that its intelligent temperature control setting, known as the heating curve, has encountered a data error or needs to be re-adjusted. d.44 Diagnostic Your boiler is having difficulty detecting the flame, which means it cannot safely keep your heating or hot water running. d.47 Diagnostic Your boiler is struggling to communicate with the external weather sensor, which means it cannot automatically adjust your heating based on the outside temperature. d.67 Diagnostic Your boiler is currently in a short, automatic waiting period between heating cycles to prevent excessive wear and tear. d.68 Diagnostic Your boiler tried to light the flame but failed on the first try, so it is pausing before attempting again. d.69 Diagnostic Your boiler has failed to light the flame after two attempts and has safely shut down to prevent gas buildup. d.71 Diagnostic Your boiler's internal settings have been configured to limit the maximum temperature of the water being sent to your radiators, which is a normal operational setting rather than a system fault. d.80 Diagnostic This code is simply an information display showing how many hours your boiler has spent providing central heating, rather than indicating a fault. d.81 Diagnostic This code is simply an information display showing the total number of hours your boiler has spent providing hot water, rather than indicating a system fault. d.82 Diagnostic This code is simply an information display showing how many times your boiler has started up to provide heating, rather than indicating a fault. d.83 Diagnostic This code is just an information log displaying how many times your boiler has started up to heat your hot water, rather than indicating a fault. d.90 Diagnostic Your boiler is currently having trouble communicating with the external heating controls, such as your thermostat or programmer. d.93 Diagnostic Your boiler's electronic control board is currently experiencing a communication mismatch or configuration error, preventing it from operating correctly. d.96 Diagnostic Your boiler has reverted to its original factory settings, which means it may need to be reconfigured to match your specific home setup. P.01 Diagnostic Your boiler is currently running in a manual testing mode that allows an engineer to adjust the burner power level for performance checks. P.02 Diagnostic Your boiler is currently running at a low power mode as part of a diagnostic test or temporary setting and is not a permanent fault. P.03 Diagnostic Your boiler is currently running a professional test mode to check if it can operate correctly at its maximum power setting. P.06 Diagnostic Your boiler is currently running an automatic 5-minute cycle to clear trapped air from the heating system, which often happens after it has been serviced or refilled. P.07 Diagnostic Your boiler is currently running an internal five-minute program to remove air bubbles from the pipes and system. S.00 Status Your boiler is currently in standby mode because it has not received a signal from your thermostat or timer to turn on the heating. S.01 Status Your boiler is currently performing a routine safety check by clearing out the internal airflow before attempting to light the flame. S.02 Status Your boiler is currently checking that water is moving through the system correctly before it attempts to light the burner. S.03 Status Your boiler is struggling to light the burner, meaning it cannot produce heat or hot water at the moment. S.04 Status Your boiler is operating normally and the burner is currently lit, meaning it is successfully heating your water or radiators. S.05 Status Your boiler is simply finishing its cooling cycle by clearing out leftover heat, which is a normal part of its operation. S.06 Status Your boiler is simply finishing its cooling cycle after the heating or hot water has been turned off, which is a normal part of its operation. S.07 Status Your boiler is simply running its pump for a short time after the heating or hot water has switched off to move remaining heat away from the unit. S.08 Status Your boiler is perfectly fine and is simply taking a short, programmed break to prevent overheating and save energy. S.10 Status Your boiler is simply detecting that you have turned on a hot water tap and is working exactly as it should to heat the water for you. S.11 Status Your boiler is currently checking that its internal air fan is working correctly before it attempts to light the burner. S.13 Status Your boiler is failing to light because it cannot detect a flame after trying to ignite. S.14 Status Your boiler is operating normally and the burner is currently lit to provide heat or hot water. S.15 Status Your boiler is currently cooling itself down after use, which is a normal part of its automatic shutdown process. S.16 Status Your boiler is simply finishing its cooling cycle to safely clear leftover gases from the flue, which is a normal part of its operation. S.17 Status Your boiler is simply finishing a routine task where it pushes leftover heat out of the system, so no action is required from you. S.30 Status Your boiler is currently in standby mode and is simply waiting for you to turn on a tap or adjust your heating thermostat. S.31 Status Your boiler is currently set to only provide hot water and is ignoring requests for central heating. S.32 Status Your boiler is struggling to push air through its internal system correctly, so it has stopped working to keep you safe. S.34 Status Your boiler has temporarily switched itself on to protect its internal pipes from freezing, which is a normal safety feature during cold weather. S.41 Status Your boiler has detected that the water pressure inside the heating system is currently too high for it to operate safely. S.53 Status Your boiler has temporarily slowed down because the water returning to the system is much cooler than the water leaving it, indicating a potential restriction in your radiators or pipes. S.54 Status Your boiler is pausing because it either has too little water pressure or is struggling to move the water around your heating system effectively. S.96 Status Your boiler's internal computer is struggling to read the temperature of the water returning from your radiators, which means it cannot regulate your heating effectively. S.98 Status Your boiler is struggling to accurately measure its internal temperature, which is causing it to pause operation as a safety precaution.