Glow Worm Boiler Fault Codes & Common Errors

Has your Glow-worm boiler issued a fault code? If you are wanting to find out more about what this may mean then this page will be able to help you.

The table of errors found below should be able to help you diagnose what the potential problem with your boiler is, however if you are still unable to find out what it means then our partnered boiler engineer experts will be able to help. If you fill in our small contact form they will be able to provide you with further information and help you come to a solution.

General Faults & Errors

This section is an overview of all of the types of errors that can occur on a Glow-worm boilers.

Fault CodePotential Cause
ConnectionPCB and user interface not communicating
F00Flow temperature sensor is faulty
F10Flow temperature sensor has short circuited
F11Return temperature sensor has short circuited
F12 / 91Cylinder temperature sensor has short circuited
F13Domestic hot water cylinder temperature sensor has short circuited
F20Overheating temperature reached
F22Low water pressure in the boiler
F23Temperature difference too great
F24The temperature has risen too fast
F25Temperature too high in flue
F27Fault in flame detection
F28Ignition unsuccessful on start up
F29Flame loss fault
F32Fan frost protection function active. The fan speed is outside the tolerance value.
F33Fan frost protection function active, fault with the air pressure
F61Gas valve control system fault
F64Electronics / sensor / analogue-to-digital converter fault
F67ASIC value sent back is incorrect
F70Invalid product code
F71Flow or return temperature sensor fault
F72Deviation in the water pressure or return temperature sensor fault
F73Water pressure sensor not connected or has short circuited fault
F74There has been an electric fault in the water pressure sensor
F75Pressure sensor fault
F77Condensate or smoke fault
F78Safety cut out on primary heat exchanger defect
F78Interruption of DHW outlet sensor
F82Gas valve switch off control fault
F83Burner temperature sensor fault
F83EEPROM fault
F84Flow or return temperature sensor fault
F85Temperature sensor fault
F85Electronics temperature too high fault
F87Electrodes fault
F88Unstable flame fault

Underfloor heating contact fault

Gas valve fault
F89Pump fault
FA9Voltage too low causing a eBUS fault