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2021 Glow Worm Boiler Error & Fault Codes


If the Glow Worm boiler flashes an error code, it is recommended you don't reset the error code yourself. In some cases resetting the error code will only be a temporary solution but at other times with your Glow Worm boiler could render it inoperable. This is why it's a good idea to try and diagnose the issue yourself – but only if you're qualified and experienced enough and know what you're doing, or call out a professional Glow Worm engineer.

An error code will flash on the display panel of your boiler. These codes are designed to help users to resolve general faults and they appear when something has gone wrong with your boiler.

Glow Worm error codes are used to diagnose problems and faults within your boiler system. Here we provide a comprehensive list of error codes for Glow Worm boilers, together with an explanation as to what each means and how to fix the problem.

Betacom Boiler Error Codes


Glow Worm boiler error codes indicate a problem your Glow Worm boiler has detected, for example a faulty part or poor flame characteristics. The Boiler Error Codes are categorised into five categories that describe what the errors are and what you need to do about them.

Below is a list of Glow Worm Betacom Boiler Error Codes. Each code contains a short explanation for the cause of the problem, what effect it can have on your boiler and what you can do to get it fixed.

Fault Code Possible Cause
Red LED onLockout - Low water pressure, Make sure pressure is above 1.5bar, reset boiler
Red LED flashingDHW temperature control knob in service position - Turn DHW control knob into temperature range
Red LED flashingOverheat - Check both overheat stats
Yellow LED flashingError - Turn DHW control knob into temperature range and turn CH temperature control knob into power (reset position) and wait for minimum of 30 seconds before turning into either summer or temperature position
Yellow LED onFlame present on the burner
Green LED onBoiler ready for operation
Green LED offNo power to boiler - Check for 230volts into the appliance, check fuse on pcb
Green LED flashingBoiler in stand-by - Reset position

Energy Boiler Error Codes


There could be many reasons for your boiler troubles, but don't worry because help can be on its way as soon as you check out our list of common Glow Worm Energy Boiler Error Codes and their solutions.

Unless you manage to decipher what the fault codes mean, then you will find it impossible to resolve what's gone wrong with your boiler repair. Check out the list below and use it to get an accurate diagnosis so that the issue can be put right.

Fault Code Possible Cause
F.00Fault: Flow temperature sensor
F.01Fault: Return temperature sensor
F.10Short circuit: Flow temperature sensor
F.11Short circuit: Return temperature sensor
F.12 and F.91Short circuit: Cylinder temperature sensor
F.13Short circuit: Domestic hot water cylinder temperature sensor
F.20Safety switch-oft. Overheating temperature reached
F.22Safety switch-oft. Low water pressure in the boiler
F.23Safety switch-oft. Temperature difference too great (NTC1/NTC2)
F.24Safety switch-oft. Temperature rise too fast
F.25Safety switch-off. Flue gas temperature too high
F.27Safety switch-off. Fault in flame detection
F.28Fault: Ignition unsuccessful when starting up
F.29Fault: Flame loss
F.32Fan frost protection function active: Fan speed outside the tolerance values
F.33Fan frost protection function active: Air pressure switch fault
FA9eBUS fault: Voltage too low
F.61Fault: Gas valve control system
F.82Fault: Gas valve switch-off control
F.83Fault: EEPROM
F.64Fault: Electronics/sensor/analogue-to-digital converter
F.85Fault: Electronics temperature too high
F.67Value sent back by ASIC is incorrect (flame slgnal)
F.88Fault: Unstable flame (analogue input)
F.70Invalid product code (DSN)
F.71Fault: Flow/return temperature sensor
F.72Fault: Deviation in the water pressure sensor/return temperature sensor
F.73Fault: Water pressure sensor not connected or has short-circuited
F.74Fault: Electrical problemin the water pressure sensor
F.75Fault: Pressure sensor
F.78The safety cut-out in the primary heat exchanger is defective
F.77Fault: Condensate or smoke
F.78Interruption to DHW outlet sensor at external controller
F.83Fault: Burner temperature sensor
F.84Fault: Flow/return temperature sensor
F.85Fault: Temperature sensor
F.88Fault: Underfloor heating contact
F.87Fault: Electrodes
F.88Fault: Gas valve
F.89Fault: Pump
ConnectionNo communication between the PCB and the user interface

Betacom A Range Boiler Error Codes


If you're not sure what Glow Worm Betacom A Range Boiler Error Codes mean then have a look at our list of codes below and use them with confidence when you need professional help to sort out any boiler problems.

If you are not familiar with fault codes then you could be at the mercy of a boiler fix company with little or no knowledge of Glow Worm products. It's absolutely essential that if your boiler displays error codes that you use a company that has experience in repairing these products.

Fault Code Possible Cause
F00Flow heating temperature sensor fault
F01Return heating temperature sensor fault
F10Flow heating temperature sensor fault
F11Return heating temperature sensor fault
F20Overheating fault
F22Low water pressure
F23Water circulation fault
F24Water circulation fault
F26Fault in gas valve
F27Flame detection fault
F28Ignition fault
F29Loss of flame during operation
F32Incorrect air pressure
F49EBUS voltage fault
F61Fault in the main board
F62Fault in the main board
F63Fault in the main board
F64Fault in the main board
F65Fault in the main board
F67Fault in the main board
F68Fluctuation of flame signal
F70User interface incompatible with the main board
F71Flow heating temperature sensor fault
F72Permanent temperature difference between flow and return heating sensors
F73Heating circuit pressure sensor fault
F74Heating circuit pressure sensor fault
F76Thermal fuse fault
F77Fault in gas valve motor
F83No water in the installation
F84Permanent temperature difference between flow and return heating sensors
F85Flow and Return heating sensor fault
F86Underfloor heating contact fault
ErrUser interface fault

Betacom C Range Boiler Error Codes


All too often, the Glow Worm Betacom C Boiler Error Codes you see popping up on your boiler's display when things go wrong can be confusing and difficult to understand. If you don't know what the fault codes mean or you don't know how it applies to you then it's going to be very difficult for the engineers who come out to fix your boiler if you phone them.

Fault Code Possible Cause
Temperature 30 flashingFault on CH thermistor
Temperature 40 flashingFault on DHW thermistor
Temperature 50 flashingFault on outside sensor
Temperature 60 flashingLow system pressure
Temperature 70 flashingFault on APS
Temperature 80 flashingOverheat open circuit
Temperature 90 flashingFlame or gas failure

Compact E Range Boiler Error Codes


If your Glow Worm Compact E Range Boiler is displaying any of the following codes, or a combination of the codes below we can help you to identify and resolve your E Range boiler problems.

Fault Code Possible Cause
No DHWCheck dhw microswitch
No C/HCheck dhw microswitch if dhw demand led is lit
No C/H but boiler is firingCheck divertor motor and cartridge
Boiler locks out within 10 secondsCheck pump proving switch, air pressure switch and overheat stat
Poor burner pressureCheck burner pressure/ignition adjustment pots on PCB

Compact S Range Boiler Error Codes


When something goes wrong in your Compact S Range Boiler, the first thing to do is check the error codes. Use this guide and you will be able to understand and solve the problem!

The Glow Worm company has made the lives of its customers easier by introducing codes that can be flashed at their boilers to let them know when different errors occur. The error codes are cryptic but can be easily diagnosed using our list below!

Fault Code Possible Cause
No DHWCheck external controls, Please test for 230V on switch live contact
No C/HCheck external controls, Please test for 230V on switch live contact
No C/H or DHWCheck external controls, Please test for 230V on switch live contact
Boiler locks out within 10 secondsCheck pump proving switch, air pressure switch and overheat stat
Poor burner pressureCheck burner pressure/ignition adjustment pots on PCB

CI Range Boiler Error Codes


We've made a list of Glow Worm CI Range Boiler Error Codes for you to use when you phone up the professionals or perhaps speak to them via email. Having this list with you will mean they know what you are talking about straight away.

The fault codes should be included in the user manual when you purchase the appliance. If you don't have a manual or it's missing the codes, please contact the manufacturer who can give you a printout.

Fault Code Possible Cause
F1Ignition fault
F2Fan/APS
F4Ignition fault
F5Overheat Fault
F6Central heating flow thermistor
F7Domestic hot water thermistor
F8Tank thermistor (N/A For this appliance)
F9Water pressure sensor fault (please contact GW technical department for further information
F10Central return flow thermistor
F11Main board connection fault
F12Connection fault between main pcb and display pcb
F13Main pcb connection fault
F14Central heating flow temperature > 95 degrees
F15Gas valve stepper motor fault
F16Flame detection fault
F17Power supply is less than 170v
F18User interface fault
F19Central heating thermistor unplugged
F20Software incompatibility

CI Plus Range Boiler Error Codes


All Glow Worm CI Plus Range Boilers have an electronic control unit that is programmed to give different error messages if it detects a problem with the boiler or domestic hot water system - this is useful as it means there are not just manuals and phone numbers to call for boiler problems, instead you can rely on a code to tell you what's wrong.

There are many different reasons why your boiler may fail to operate and produce no hot water or heat. Below you can find a list of Glow Worm CI Plus boiler error codes.

Fault Code Possible Cause
F1Ignition fault
F2Fan/APS
F3Air fault
F4Ignition fault
F5Overheat Fault
F6Central heating flow thermistor
F7Domestic hot water thermistor
F8Tank thermistor (N/A For this appliance)
F9Water pressure sensor fault (please contact GW technical department for further information
F10Central return flow thermistor
F11Main board connection fault
F12Connection fault between main pcb and display pcb
F13Main pcb connection fault
F14Central heating flow temperature > 95 degrees
F15Gas valve stepper motor fault
F16Flame detection fault
F17Power supply is less than 170v
F18User interface fault
F19Central heating thermistor unplugged
F20Software incompatibility

CXI Range Boiler Error Codes


There are a number of error codes which may show up on your Glowworm CXi boiler. This makes sense if you think about it, as the boiler is a complex device with many different parts that can go wrong, so it's important to be able to identify which code represents which problem.

There are several different error codes that the Glow Worm CXI Range boiler could display, and they all mean different things, so it is sometimes hard to work out just what the problem is. This guide will help you decipher them and work out what needs to be done.

Fault Code Possible Cause
F1Ignition fault
F2Fan
F3Fan unable to reach ignition speed
F4Ignition fault
F5Overheat Fault
F6Central heating flow thermistor
F7Domestic hot water thermistor
F8Tank thermistor (N/A For this appliance)
F9Water pressure sensor fault (please contact GW technical department for further information
F10Central return flow thermistor
F11Main board connection fault
F12Connection fault between main pcb and display pcb
F13Main pcb connection fault
F14Central heating flow temperature > 95 degrees
F15Gas valve stepper motor fault
F16Flame detection fault
F17Power supply is less than 170v
F18User interface fault
F19Central heating thermistor unplugged
F20Software incompatibility
F24Central heating return temperature > 90 degrees
F25Poor circulation
F26Poor circulation

Flexicom CX Range Boiler Error Codes


Below is an index to Glow Worm Flexicom CX Range boiler error codes that you can use if your boiler is displaying a fault code and you need to know what it means. If your boiler or heating system is giving you problems in the form of error codes or flashing lights, the Glow Worm range is ready with the relevant information to help you get on top of the problem and back to enjoying your heating system once again.

Fault Code Possible Cause
F1Ignition fault
F3Fan unable to reach ignition speed
F4Ignition fault
F5Overheat Fault
F6Central heating flow thermistor
F7Domestic hot water thermistor
F9Water pressure sensor fault, blocked flow filter or pump fault
F10Central return flow thermistor
F11Flow and or return thermistor fault
F13PCB memory or sensing fault
F14Gas valve control defective
F15E-bus voltage failure
F22Low water pressure or ignition temperature rise too slow
F24Central heating return temperature > 90 degrees
F25Circulation fault
F43Generic error
F70Software incompatible
F73Unable to see pump activate
F77Condensate pump error (optional)

Flexicom HX Range Boiler Error Codes


There are many different error codes relating to Glow Worm Flexicom HX Range Boiler boilers but there are a few that occur more frequently than others. If you are experiencing any of the errors below on your Glow Worm Flexicom HX Range Boiler, our troubleshooting guide will help you find a solution so that your boiler can be operating again as soon as possible.

Fault Code Possible Cause
F1Ignition fault
F3Fan unable to reach ignition speed
F4Ignition fault
F5Overheat Fault
F6Central heating flow thermistor
F9Low water pressure Sensor
F10Central return flow thermistor
F11Flow and or return thermistor fault
F13PCB memory or sensing fault
F14Gas valve control defective
F15E-bus voltage failure
F22Low water pressure or ignition temperature rise too slow
F25Circulation fault
F43Generic error
F70Software incompatible
F73Unable to see pump activate
F77Condensate pump error (optional)

Flexicom SX Range Boiler Error Codes


Each time you get an error message from your Flexicom SX there is information provided on what to look for and how to rectify the situation. Take a look at our list of Flexicom SX range boiler error codes below, familiarity with this list will give you piece of mind, and help you deal with your boiler more effectively.

Fault Code Possible Cause
F1Ignition fault
F3Fan unable to reach ignition speed
F4Ignition fault
F5Overheat Fault
F6Central heating flow thermistor
F7Domestic hot water thermistor
F9Low water pressure Sensor
F10Central return flow thermistor
F11Flow and or return thermistor fault
F13PCB memory or sensing fault
F14Gas valve control defective
F15E-bus voltage failure
F22Low water pressure or ignition temperature rise too slow
F25Circulation fault
F43Generic error
F70Software incompatible
F73Unable to see pump activate
F77Condensate pump error (optional)

HXI Range Boiler Error Codes


Boilers need regular servicing to keep them in top condition and this is why a Glow Worm HXI Range Boiler Error Codes list could be handy for our heating professionals. Knowing what these mean can help to make the correct diagnosis and get your heating and hot water back up to running perfectly again.

Have you got a Glow Worm HXI Range Boiler Error Code and don't know what it means? Use our code list below to get help with boiler problems.

Fault Code Possible Cause
F1Ignition fault
F2Fan
F3Fan unable to reach ignition speed
F4Ignition fault
F5Overheat Fault
F6Central heating flow thermistor
F7Domestic hot water thermistor
F8Tank thermistor (N/A For this appliance)
F9Earlier models only (please contact GW technical department for further information)
F10Central return flow thermistor
F11Main board connection fault
F12Connection fault between main pcb and display pcb
F13Main pcb connection fault
F14Central heating flow temperature > 95 degrees
F16Flame detection fault
F17Power supply is less than 170v
F18User interface fault
F19Central heating thermistor unplugged
F20Software incompatibility
F24Cental heating return temperature > 90 degrees
F25Poor circulation
F26Poor circulation

SI Range Boiler Error Codes


Error code numbers are used by Glow Worm to denote faults with their SI Range. The first thing to remember is that these codes are specific to the SI Range of boilers.

This list of fault codes will help you get a better understanding on your boilers error codes and what they mean.

Fault Code Possible Cause
F1Ignition fault
F2Fan/APS
F4Ignition fault
F5Overheat Fault
F6Central heating flow thermistor
F7Domestic hot water thermistor
F8Tank thermistor (N/A For this appliance)
F9Water pressure sensor fault (please contact GW technical department for further information)
F10Central return flow thermistor
F11Main board connection fault
F12Connection fault between main pcb and display pcb
F13Main pcb connection fault
F14Central heating flow temperature > 95 degrees
F15Gas valve stepper motor fault
F16Flame detection fault
F17Power supply is less than 170v
F18User interface fault
F19Central heating thermistor unplugged
F20Software incompatibility

SXI Range Boiler Error Codes


Glow Worm SXI Range Boiler Error Codes are the letters and numbers you see on the boiler control panel or display when there is a fault. If your boiler keeps making strange noises, flashing lights or doesn't function as planned after it has ignited you should take it seriously.

The error codes will appear on the display panel on the boiler (there may be more than one) and describe exactly what is wrong. Some problems can be easily fixed, others may well require a qualified Glow worm engineer to come out and take a look at your boiler.

Fault Code Possible Cause
F1Ignition fault
F2Fan
F3Fan unable to reach ignition speed
F4Ignition fault
F5Overheat Fault
F6Central heating flow thermistor
F7Domestic hot water thermistor
F8Tank thermistor (N/A For this appliance)
F9Water pressure sensor fault (please contact GW technical department for further information)
F10Central return flow thermistor
F11Main board connection fault
F12Connection fault between main pcb and display pcb
F13Main pcb connection fault
F14Central heating flow temperature > 95 degrees
F15Gas valve stepper motor fault
F16Flame detection fault
F17Power supply is less than 170v
F18User interface fault
F19Central heating thermistor unplugged
F20Software incompatibility
F24Cental heating return temperature > 90 degrees
F25Poor circulation
F26Poor circulation

Ultracom2 CXI Range Boiler Error Codes


Fault codes are there to provide an easy way to understand what the CXI is trying to tell you. A blinking light is usually a sign that there is a problem somewhere and needs to be addressed immediately.

If you're not sure what Glow Worm Ultracom2 CXI Boiler Error Codes mean then have a look at our list of boiler codes below and use them with confidence when you need professional help to sort out any boiler problems.

Fault Code Possible Cause
F00Flow heating temperature sensor fault
F01Return heating temperature sensor fault
F10Flow heating temperature sensor fault
F11Return heating temperature sensor fault
F20Overheating fault
F22Low water pressure
F23Water circulation fault
F24Water circulation fault
F26Fault in gas valve
F27Flame detection fault
F28Ignition fault
F29Loss of flame during operation
F32Incorrect air pressure
F49EBUS voltage fault
F61Fault in the main board
F62Fault in the main board
F63Fault in the main board
F64Fault in the main board
F65Fault in the main board
F67Fault in the main board
F68Fluctuation of flame signal
F70User interface incompatible with the main board
F71Flow heating temperature sensor fault
F72Permanent temperature difference between flow and return heating sensors
F73Heating circuit pressure sensor fault
F74Heating circuit pressure sensor fault
F76Thermal fuse fault
F77Fault in gas valve motor
F83No water in the installation
F84Permanent temperature difference between flow and return heating sensors
F85Flow and Return heating sensor fault
F86Underfloor heating contact fault
ErrUser interface fault

Ultracom2 SXI Range Boiler Error Codes


There are a various Glow Worm Ultracom2 SXI Range boiler error codes which can appear on your boiler's display. If you're not sure what the code means or are having problems then we can help provide the meaning as well as how to fix them.

For people who don't know what Ultracom2 SXI fault codes mean then have a look at our list of codes below and use them with confidence when you need professional help to sort out any boiler problems.

Fault Code Possible Cause
F00Flow heating temperature sensor fault
F01Return heating temperature sensor fault
F10Flow heating temperature sensor fault
F11Return heating temperature sensor fault
F20Overheating fault
F22Low water pressure
F23Water circulation fault
F24Water circulation fault
F26Fault in gas valve
F27Flame detection fault
F28Ignition fault
F29Loss of flame during operation
F32Incorrect air pressure
F49EBUS voltage fault
F61Fault in the main board
F62Fault in the main board
F63Fault in the main board
F64Fault in the main board
F65Fault in the main board
F67Fault in the main board
F68Fluctuation of flame signal
F70User interface incompatible with the main board
F71Flow heating temperature sensor fault
F72Permanent temperature difference between flow and return heating sensors
F73Heating circuit pressure sensor fault
F74Heating circuit pressure sensor fault
F76Thermal fuse fault
F77Fault in gas valve motor
F83No water in the installation
F84Permanent temperature difference between flow and return heating sensors
F85Flow and Return heating sensor fault
F86Underfloor heating contact fault
ErrUser interface fault

Ultracom2 35 Store Boiler Error Codes


We have a list of Glow Worm Ultracom2 35 Store Boiler Error Codes listed below together with an explanation and advice for each so that you can diagnose problems on boilers quickly and easily.

The Ultracom 2 35 store fault codes are a little different than a standard boiler error code list because they act more like an instruction manual for your boiler.

Fault Code Possible Cause
F00Flow heating temperature sensor fault
F01Return heating temperature sensor fault
F02Hot water temperature sensor fault
F03Storage tank temperature sensor fault
F10Flow heating temperature sensor fault
F11Return heating temperature sensor fault
F12Hot water temperature sensor fault
F13Storage tank temperature sensor fault
F20Overheating fault
F22Low water pressure
F23Water circulation fault
F24Water circulation fault
F26Fault in gas valve
F27Flame detection fault
F28Ignition fault
F29Loss of flame during operation
F32Incorrect air pressure
F49EBUS voltage fault
F61Fault in the main board
F62Fault in the main board
F63Fault in the main board
F64Fault in the main board
F65Fault in the main board
F67Fault in the main board
F68Fluctuation of flame signal
F70User interface incompatible with the main board
F71Flow heating temperature sensor fault
F72Permanent temperature difference between flow and return heating sensors
F73Heating circuit pressure sensor fault
F74Heating circuit pressure sensor fault
F76Thermal fuse fault
F77Fault in gas valve motor
F79Storage tank temperature sensor fault
F81Overheating of hot water circuit
F83No water in the installation
F84Permanent temperature difference between flow and return heating sensors
F85Flow and Return heating sensor fault
F86Underfloor heating contact fault
ErrUser interface fault

Ultracom CXI Range Boiler Error Codes


When there is an issue with the Glow Worm Ultracom CXI Range Boiler Error Codes then a red light will come on next to the fault. Any errors that occur on this part of the boiler will be displayed in sequence; the first being boiler error code 1 and so on.

Take a look at the list of Glow Worm Ultracom CXI Range Boiler Error Codes below and if you're still not sure if you have a problem or what the problem might mean then please do not hesitate to either search for your boiler's brand name in the search box over on the left hand side of this page or browse around this site for more boiler fault codes.

Fault Code Possible Cause
F1Ignition fault
F3Fan unable to reach ignition speed
F4Ignition fault
F5Overheat Fault
F6Central heating flow thermistor
F9Water pressure sensor fault, blocked flow filter or pump fault
F10Central return flow thermistor
F11Main board connection fault
F13PCB memory or sensing fault
F14Gas valve control defective
F15E-bus voltage failure
F22Low water pressure or ignition temperature rise too slow
F25Circulation fault
F43Generic error
F70Software incompatible
F73Unable to see pump activate
F77Condensate pump error (optional)
No display or Erloose connection X51

Ultracom CX Range Boiler Error Codes


The Ultracom CX boilers are renowned throughout the industry for being excellent boilers with excellent boilers with their reliability, efficiency and comfort features.

There are a number of Glow Worm Ultracom CX Range boiler error codes that you may come across. We're going to look at these together so you'll know what they mean and can have confidence when you call in a qualified engineer to fix them for you.

Fault Code Possible Cause
F1Ignition fault
F3Fan unable to reach ignition speed
F4Ignition fault
F5Overheat Fault
F6Central heating flow thermistor
F9Water pressure sensor fault, blocked flow filter or pump fault
F10Central return flow thermistor
F11Main board connection fault
F13PCB memory or sensing fault
F14Gas valve control defective
F15E-bus voltage failure
F22Low water pressure or ignition temperature rise too slow
F25Circulation fault
F43Generic error
F70Software incompatible
F73Unable to see pump activate
F77Condensate pump error (optional)
No display or Erloose connection X51

Ultracom HXI Range Boiler Error Codes


A list of Glow Worm Ultracom HXI Range Boiler Error Codes that you can find on your boiler user manual. You will be able to use the error codes with confidence when you need professional help to sort out any boiler problems.

These fault codes can lead to an unexpected breakdown which you will not be prepared for without help, and it's important to know how to solve them.

Fault Code Possible Cause
F1Ignition fault
F3Fan unable to reach ignition speed
F4Ignition fault
F5Overheat Fault
F6Central heating flow thermistor
F9Water pressure sensor fault, blocked flow filter or pump fault
F10Central return flow thermistor
F11Main board connection fault
F13PCB memory or sensing fault
F14Gas valve control defective
F15E-bus voltage failure
F22Low water pressure or ignition temperature rise too slow
F25Circulation fault
F43Generic error
F70Software incompatible
F73Unable to see pump activate
F77Condensate pump error (optional)
No display or Erloose connection X51

Ultracom SXI Range Boiler Error Codes


If your Glow Worm Ultracom SXI Range Boiler error code then it's triple combination of numbers and letters can appear in a few different ways. The most common Glow Worm Ultracom SXI Range Boiler error code that you'll come across is the three digit type. These are normally easy to fix for an engineer and you will find most of the numbers below linked to their related instruction manual.

Fault Code Possible Cause
F1Ignition fault
F3Fan unable to reach ignition speed
F4Ignition fault
F5Overheat Fault
F6Central heating flow thermistor
F9Water pressure sensor fault, blocked flow filter or pump fault
F10Central return flow thermistor
F11Main board connection fault
F13PCB memory or sensing fault
F14Gas valve control defective
F15E-bus voltage failure
F22Low water pressure or ignition temperature rise too slow
F25Circulation fault
F43Generic error
F70Software incompatible
F73Unable to see pump activate
F77Condensate pump error (optional)
No display or Erloose connection X51

Ultrapower SXI Range Boiler Error Codes


If you're not sure what an error code means or if you think your boiler has an error code stuck on the display, then have a look at our list of Glow Worm Ultrapower SXI Range Boiler Error Codes below. We have the most common errors and what the fault might be. You can also find the fault location in the boiler manual and for any other problems that you encounter.

Fault Code Possible Cause
F1Ignition fault
F3Fan unable to reach ignition speed
F4Ignition fault
F5Overheat Fault
F6Central heating flow thermistor
F9Water pressure sensor fault, blocked flow filter or pump fault
F10Central return flow thermistor
F11Main board connection fault
F13PCB memory or sensing fault
F14Gas valve control defective
F15E-bus voltage failure
F22Low water pressure or ignition temperature rise too slow
F25Circulation fault
F43Generic error
F70Software incompatible
F73Unable to see pump activate
F77Condensate pump error (optional)
No display or Erloose connection X51

Xtramax HE Range Boiler Error Codes


Xtramax HE range boilers are popular and can be found throughout the UK. Glow Worm have produced an Xtramax with a wide variety of different stats, and each has its own error codes.

If any of the Glow Worm Xtramax HE Range Boiler error codes indicate a fault, we have a list of possible reasons why these could be happening below.

Fault Code Possible Cause
F1Ignition fault
F2Fan
F3Fan
F4Ignition fault
F5Overheat Fault
F6Central heating flow thermistor
F7Domestic hot water thermistor
F8Tank thermistor
F9Water pressure sensor fault (please contact GW technical department for further information)
F10Central return flow thermistor
F11Main board connection fault
F12User interface connection fault
F13PCB memory or sensing fault
F14Gas valve control defective
F16Flame detection fault
F17Power supply is less than 170v
F18User interface fault
F19Central heating thermistor unplugged
F20Software incompatibility
F23Water circulation fault
F24Cental heating return temperature > 90 degrees
F25Maximum temperature rise slope
F26Maximum delta temperature

Xtrafast 96/120 Range Boiler Error Codes


This is a list of Glow Worm Xtrafast 96/120 Range Boiler Error Codes, and their meaning. This list applies to Glow Worm boilers made in the UK in 1996 and later. If you have a problem with your Glow Worm boiler, click on the relevant code below to find out further information.

Fault Code Possible Cause
F00No fault
F02Air flow fault
F04Ignition fault - flame detection
F05Overheating
F06Central heating thermistor/wiring fault
F07Domestic hot water thermistor/wiring fault
F08Storage vessel thermistor/wiring fault
F09System pressure sensor fault
F10Fan fault
F11Poor circulation
F12User interface fault
F13Main pcb fault
F14Central heating flow temperature > 97 degrees
F15Gas mechanism fault
F20Communication fault

Xtrafast 96/120E1 Range Boiler Error Codes


Error Codes from Xtrafast 96/120E1 boilers can be very useful, especially if you are not familiar with all of them. If your boiler is running you will know already that there is something wrong.

There is a complete list of Glow Worm Xtrafast 96/120E1 Range Boiler Error Codes below. Each error code has a meaning and helps the engineer identify the fault condition quicker, this is why it is very important to provide an error code or fault description when contacting a boiler repair specialist.

Fault Code Possible Cause
F00No fault
F02Air flow fault
F04Ignition fault - flame detection
F05Overheating
F06Central heating thermistor/wiring fault
F07Domestic hot water thermistor/wiring fault
F08Storage vessel thermistor/wiring fault
F09System pressure sensor fault
F10Fan fault
F11Poor circulation
F12User interface fault
F13Main pcb fault
F14Central heating flow temperature > 97 degrees
F15Gas mechanism fault
F20Communication fault
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