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Glow-Worm Boiler Fault Codes and Errors
Is your glow-worm boiler displaying some faulty codes that you are having a hard time cracking? Well, you need not worry anymore as you have come to the right place. In this guide, we will explain the meaning of the different fault codes that your boiler may be displaying and their possible causes.
Glow-Worm Boiler General Fault Codes and Errors
| Fault
Code |
Description | Possible Cause |
| F00 | Faulty flow temperatures sensor | The NTC plug is loose or not plugged in, or is defective |
| F01 | Faulty return temperature sensor | The NTC plug is loose or not plugged in, or is defective |
| F10 | The flow temperature sensor is short-circuited | The NTC sensor is defective, or there is a short circuit in the wiring |
| F11 | There is a short-circuit in the return temperature sensor | The NTC sensor is defective, or there is a short circuit in the wiring |
| F12 & F91 | There is a short circuit in the cylinder temperature sensor | The NTC sensor is defective, or there is a short circuit in the wiring |
| F13 | A short circuit in the DHW cylinder temperature sensor | The NTC sensor is defective, or there is a short circuit in the wiring |
| F20 | Excessive temperature detected in the boiler resulting in a safety switch-off | Incorrect earth connection, faulty ignition electrode, or a defective flow/return NTC sensor |
| F22 | Safety switch-off due to low water pressure in the boiler | Insufficient water in the system or the water pressure sensor is defective |
| F23 | The temperature difference between flow and return sensors in the boiler is too big, prompting a safety switch off | The pump is blocked or is faulty, or the flow and return sensors are switched |
| F24 | Temperature rise is too rapid | Faulty pump, presence of air in the system, or system pressure is too low |
| F25 | Excessive flue gas temperature | Faulty optional flue gas safety temperature limiter |
| F27 | Flame detection error | Faulty flame detection electrode or the boiler electronics are moist |
| F28 | Ignition failure | Faulty detection electrode or there is no gas supply, or gas flow pressure is too low |
| F29 | Flame loss | Gas supply temporarily stopped, or the ignition transformer registered a spark failure |
| F32 | The fan protection feature is active due to fan speed being outside tolerable values | The fan is blocked, faulty PCB unit, or fan not correctly plugged in |
| F33 | The fan frost protection feature is active due to an air pressure switch fault | Faulty pressure monitor or fan speed set too high, resulting in inadequate air supply |
| FA9 | Low voltage resulting in an eBUS fault | The eBUS is short-circuited or overloaded |
| F61 | Faulty gas control system | The gas valve is defective, or there is a short-circuit in the valve connection |
| F64 | Faulty electronics or sensors or analogue-to-digital converter | The boiler has defective electronics, or the flow/return sensor is short-circuited |
| F67 | Incorrect flame signal | Faulty electronics or implausible flame signal |
| F70 | The DSN product code is invalid | The PCB and display units were replaced at the same time, and the DSN number was not reset |
| F71 | The flow/return sensor is displaying a constant value | The flow/return sensor is defective or incorrectly placed |
| F72 | Notable deviation detected in water pressure/ return temperature sensor | The temperature difference in the flow/return NTC is too big. The return sensor could also be defective |
| F73 | Faulty water pressure sensor | The water pressure sensor is defective, or not connected, or is short-circuited |
| F74 | Faulty water pressure sensor due to an electrical fault | The connection to the water pressure sensor has a short-circuit, or the sensor has an internal fault |
| F75 | Faulty pressure sensor | The pressure switch may be defective |
| F77 | Presence of condensate or smoke fault in the boiler | The condensate pipe is blocked, or the flue non-return flap is defective |
| F78 | Defective safety cut-out in the primary heat exchanger | There is a mismatch between the safety cut-out feedback and the gas valve feedback |
| F78 | The DHW outlet sensor has been interrupted at the external controller | The hot water NTC is not connected |
| F83 | EEPROM error | Defective boiler electronics |
| F83 | Faulty burner temperature sensor | The burner temperature sensor is defective, or there is insufficient water in the boiler system |
| F84 | Faulty flow/return temperature sensor | The flow and return sensors have been inverted or incorrectly installed |
| F85 | Faulty temperature sensor | The temperature sensor is incorrectly installed, or the flow and return sensors have been installed on the same pipe |
| F85 | The boiler electronics are overheating | The boiler electronics are defective |
| F.87 | Faulty electrodes | The electrodes are faulty or incorrectly connected |
| F88 | Faulty gas valve | The gas valve is defective, not connected, or is connected incorrectly |
| F88 | Faulty underfloor heating contact | The underfloor heating contact is open, disconnected, or defective |
| F88 | The flame is unstable | Presence of air in the gas, low gas pressure, faulty electrodes, or incorrect air ratio |
| F89 | Pump fault | The pump is not connected, is incorrectly connected, or there is a short-circuit in the cable harness |