Glow Worm Error Codes, Faults & Fixes
Glow Worm boiler error codes & fault code guide for 2024
This article deals with all the Glow Worm error codes you can face from your boiler. The following glow worm error codes contain models, such as Betacom, Ultracom, Flexicom, Xtramax, Compact, Ci, and Xtrafast.
If you are experiencing one or more of these Glow Worm error codes and your boiler is over 10 years old then it may be time to consider a new boiler.
If your boiler is less than 10 years old then we strongly suggest getting in touch with Glow worm or a Gas Safe registered heating engineer when you get your Glow Worm boiler service to discuss what the best option is moving forward
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Glow Worm Boiler Error Codes
See our list of Glow Worm error codes to help you quickly diagnose any issues with your boiler. Be aware of common problems you can fix yourself too like low boiler pressure or a frozen boiler condensate pipe, which can save you money on expensive callouts!
Other things that also may not crop up but still cause you issues are things like a boiler timer not working, which could cost you money in the long run by turning your boiler on when you don’t need it!
F.00
Flow temperature sensor
F.10 and F.11
The flow temperature sensor has short-circuited
F.12 and F.91
The cylinder temperature sensor has short-circuited
F.13
The domestic hot water cylinder temperature sensor has short-circuited
F.20
Safety switch-off process due to overheating
F.22
Safety switch-off process due to boiler low water pressure
F.23
The safety switch-off process due to temperature difference is too large
F.24
Safety switch-off process due to temperature rising too fast
F.25
Safety switch-off process due to flue gas temperature being too high
F.27
Safety switch-off process due to fault in the flame
F.28
Unsuccessful ignition when starting up – Possible frozen condensate pipe
F.29
Loss of flame – Possible frozen condensate pipe
F.32
The fan frost protection function is active, meaning that fan speed is outside its tolerance levels
FA9
eBus fault because the voltage is too low
F.61
There is a fault with the gas valve control system
F.64
Fault with the electronics, sensor, or analogue to digital converter
F.67
The value sent by ASIC is incorrect
F.70
Invalid product code or DSN
F.71
Fault with flow or return temperature sensor
F.72
Change in the return temperature sensor or water pressure sensor
F.73
The water pressure sensor has short-circuited or is not connected
F.75
Fault with the pressure sensor
F.77
The safety cut out located in the
F.82
There is a fault with the fast valve switch
F.83
EEPROM fault due to defective electronics
It could also be a fault to the burner temperature sensor
F.84
Return or temperature sensor fault
F.85
Temperature sensor fault
F.87
Electrodes fault
F.88
Unstable flame in analogue input, gas valve fault or underfloor heating contact fault
F.89
Pump fault
If your boiler ever puts up the following glow worm error codes, then you should know that there is a problem with your condensate pipe. A frozen condensate pipe is classed as a blockage and will stop your boiler from working and possibly show one of the following error codes:
- Glow Worm F1
- Glow Worm F4
- Glow Worm F28
- Glow Worm F29
Glow Worm Fault Codes & DIY Fixes If Possible
Here is a list of the exact faults from Glow Worm boilers – Most faults will require a Gas Safe registered heating engineer so that is the reason why there isn’t a suggestion for what you should do in these scenarios.
| Fault Codes | Boiler Model | Issue | DIY Fix | |
| F25 | Xtramax HE Range | Maximum temperature rise slope | ||
| F26 | Xtramax HE Range | Maximum delta temperature | ||
| F00 | Xtrafast 96/120 Range | |||
| F00 | Xtrafast 96/120 Range / Xtrafast 96/120E1 Range | No fault | ||
| F02 | Xtrafast 96/120 Range / Xtrafast 96/120E1 Range | Air flow fault | ||
| F05 | Xtrafast 96/120 Range / Xtrafast 96/120E1 Range | Overheating | ||
| F06 | Xtrafast 96/120 Range / Xtrafast 96/120E1 Range | Central heating thermistor or wiring fault | ||
| F08 | Xtrafast 96/120 Range / Xtrafast 96/120E1 Range | Storage vessel thermistor or wiring fault | ||
| F09 | Xtrafast 96/120 Range / Xtrafast 96/120E1 Range | System pressure sensor fault | ||
| F10 | Xtrafast 96/120 Range / Xtrafast 96/120E1 Range | Fan fault | ||
| F13 | Xtrafast 96/120 Range / Xtrafast 96/120E1 Range | Main PCB fault | ||
| F14 | Xtrafast 96/120 Range / Xtrafast 96/120E1 Range | The central heating flow temperature is higher than 97 degrees. | ||
| F15 | Xtrafast 96/120 Range / Xtrafast 96/120E1 Range | Gas mechanism fault | ||
| F20 | Xtrafast 96/120 Range / Xtrafast 96/120E1 Range | Communication fault | ||
| F13 | Flexicom cx / hx / sx / Ultracom cxi / cx / hxi / sxi / Xtramax HE | PCB memory fault | ||
| F14 | Flexicom cx / hx / sx / Ultracom cxi / cx / hxi / sxi / Xtramax HE | Gas valve control is defective | ||
| F15 | Flexicom cx / hx / sx / Ultracom cxi / cx / hxi / sxi / Xtramax HE | E-bus voltage failure | ||
| F25 23 | All Boilers | Circulation fault | ||
| F43 | Flexicom cx / hx / sx / Ultracom cxi / cx / hxi / sxi | Generic error | ||
| F70 | Flexicom cx / hx / sx / Ultracom cxi / cx / hxi / sxi | Software incompatibility | ||
| F73 | Flexicom cx / hx / sx / Ultracom cxi / cx / hxi / sxi | Unable to see pump activate | ||
| F77 | Flexicom cx / hx / sx / Ultracom cxi / cx / hxi / sxi | Condensate pump error | ||
| F02 / F12 | Ultracom₂ 35 Store | Hot water temperature sensor fault | ||
| F03 / F13 / F79 | Ultracom₂ 35 Store | Storage tank temperature sensor fault | ||
| F81 | Ultracom₂ 35 Store | Overheating of the hot water circuit | ||
| No display or Er | All Ultracom | loose connection X51 | ||
| F24 | Xtramax HE Range | Central heating return temperature is higher than 90 degrees | ||
| F25 F26 F11 | cxi / hxi / sxi / Xtrafast 96/120 / Xtrafast 96/120E1 | Poor circulation | ||
| F3 | Ci range | Air fault | ||
| F2 F3 | cxi / sxi / hxi range/ Xtramax HE | Fan fault | ||
| F3 | cxi / sxi range / Flexicom cx / hx / sx / hxi / Ultracom cxi / cx / hxi / sxi / Ultrapower sx | Fan unable to attain ignition speed | ||
| F9 | Flexicom cx / hx / sx / hxi / Ultracom cxi / cx / hxi / sxi | Blocked flow filter, fault with water pressure sensor or pump | ||
| F11 | Flexicom cx / hx / sx | Return or flow thermistor fault | ||
| F2 | Ci range (plus)/ Si range | Fan or APS fault | ||
| F10 | All Boilers | Central return flow thermistor | ||
| F11 | All Boilers | Fault on main board connection | ||
| F12 | Ci (plus) / cxi / hxi / si / sxi range | Connection fault between display PCB and main PCB | ||
| F13 | Ci (plus) / cxi / hxi / si / sxi range | Main PCB connection fault | ||
| F14 | Ci (plus) / cxi / hxi / si / sxi range | Central heating flow temperature | ||
| F15 | Ci (plus) / cxi / hxi / si / sxi range | Gas valve stepper motor fault | ||
| F17 | Ci (plus) / cxi / hxi / si / sxi range / Xtramax HE | Power supply less than required 170 volts | ||
| F19 | Ci (plus) / cxi / hxi / si / sxi range / Xtramax HE | Central heating thermistor unplugged | ||
| F20 | Ci (plus) / cxi / hxi / si / sxi range / Xtramax HE | Software incompatibility | ||
| F24 | cxi / hxi / sxi range / Flexicom cx | Central heating return temperature is higher than 90 degrees. | ||
| Compact e/s | No C/H | Check DHW microswitch to ensure DHW demand LED is lit. | ||
| Compact e/s | No C/H, but the boiler is firing | Check diverter cartridge and motor | ||
| Compact e/s | The boiler locks out within 10 seconds. | Check pump proving switch, overheat state, and air pressure switch. | ||
| Compact e/s | Poor burner pressure | Check burner pressure and ignition electrode adjustment posts on PCB | ||
| Temperature 30 flashing | Betacom C | The central heating thermistor has a fault | ||
| Temperature 40 flashing | Betacom C | Fault on Domestic Hot Water Thermistor | ||
| Temperature 50 flashing | Betacom C | Fault on the outside sensor | ||
| Temperature 60 flashing | Betacom C | Low system pressure | ||
| Temperature 70 flashing | Betacom C | Fault on APS | ||
| Temperature 80 flashing | Betacom C | Overheat open circuit | ||
| Temperature 90 flashing | Betacom C | Gas or flame failure | ||
| No DHW | Compact e/s | DHW is inactive | Check DHW microswitch | |
| F70 | Betacom, Ultracom2 cxi/sxi/35 | The user interface is incompatible with the main board | The user interface needs to be changed | |
| F72 F84 | Betacom, Ultracom2 cxi/sxi/35 | The permanent temperature difference between return and heating flow sensors has a fault. | ||
| F73 F74 | Betacom, Ultracom2 cxi/sxi/35 | Heating circuit pressure sensor fault | ||
| F76 & F83 | Betacom, Ultracom2 cxi/sxi/35 | Fault with thermal fuse | ||
| F85 | Betacom, Ultracom2 cxi/sxi/35 | Underfloor heating contact fault | ||
| ERR F12 F18 | All Boilers | User interface fault | ||
| F00, F10, F7 | Betacom, Ultracom2 cxi/sxi/35 | An issue with the flow heating temperature sensor | ||
| F01 F11 | Betacom, Ultracom2 cxi/sxi/35 | Return heating temperature sensor fault | ||
| F20 | Betacom, Ultracom2 cxi/sxi/35 | Overheating fault | ||
| F9 F22 | Betacom, Ultracom2 cxi/sxi/hxi/35, Flexicom cx/hx/sx | Ignition temperature rise too slow or Low water pressure | ||
| F26 F7 | Betacom, Ultracom2 cxi/sxi/35 | Gas valve fault | ||
| F27 F16 | Betacom, Ultracom2 cxi/sxi/35/CI/hxi, Xtramax HE | Flame detection fault | ||
| F28 F1 F4 | All boilers | Ignition fault | ||
| F29 | Betacom, Ultracom2 cxi/sxi/35 | Loss of flame during operation | ||
| F32 | Betacom, Ultracom2 cxi/sxi/35 | Incorrect air pressure | ||
| F49 | Betacom, Ultracom2 cxi/sxi/35 | EBUS voltage fault | ||
| F61 F62 F63 F64 F65 F67 | Betacom, Ultracom2 cxi/sxi/35 | Fault in the main board | ||
| F68 | Betacom, Ultracom2 cxi/sxi/35 | Fluctuation of flame signal | ||
| Yellow LED on | Betacom | Flame is present on the burner | ||
| Green LED On | Betacom | The boiler is ready for operation | ||
| Green LED off | Betacom | There is no power to the boiler | Check the power connection to the boiler and that the right fuse is connected on the PCB. | |
| Red LED on | Betacom | Lockout due to low water pressure | Increase water pressure to 1.5 and reset the boiler | |
| Red LED flashing | Betacom | Overheating | Check stats on overheating | |
| Yellow LED flashing | Betacom | The domestic hot water temperature is off | Turn the DHW control knob to the temperature range. Turn the central heating temperature control knob into reset position and wait for 30 seconds before switching to temperate or summer position. |
Conclusion
These Glow Worm boiler error codes can appear when the pipe is frozen. Frozen pipes tend to occur during the colder months, especially if the pipes are run outdoors.
You can fix this issue yourself; however, if you are not confident enough or do not have the required skills to fix the boiler problem indicated by the fault code, whether it’s a water pressure sensor fault, heat exchanger, or short circuit, you will need to contact a licensed boiler repair or Gas Safe engineer.
With this article on Glow Worm error codes, you should have no problem ascertaining what fault your combi boiler has at that very moment. Understanding the Glow Worm error codes can save you quite some time troubleshooting.
