| Fault Code | Possible Cause | Solution | Resources |
|---|---|---|---|
| E09 | Gas valve wiring fault | ||
| E10 | Outdoor sensor error | ||
| E15 | Gas valave connection fault | ||
| E20 | Central heating thermistor sensor fault | ||
| E28 | Flue thermistor fault | ||
| E40 | Central heating return thermistor fault | ||
| E50 | Domestic hot water sensor fault | ||
| E53 | Flue obstruction | ||
| E55 | Calibration required | ||
| E78 | Water pressure sensor fault | ||
| E83 / 84 / 85 / 86 / 87 | No communication between room controller and boiler | ||
| E92 | Combustion test alarm during auto-setting | ||
| E109 | Poor circulation | ||
| E110 | Boiler overheat tripped | ||
| E117 | System pressure high (>2.9 bar) | ||
| E118 | System pressure low | ||
| E119 | System pressure low | ||
| E125 | Primary water circulation fault | ||
| E128 | Loss of flame during operation | ||
| E129 | Loss of flame during calibration | ||
| E130 | Flue thermostat sensor tripped (lockout) | ||
| E131 | Flue overheat lockout | ||
| E133 | Ignition fault | ||
| E135 | Internal error | ||
| E151 | PCB error | ||
| E152 | PCB error | ||
| E154 | Primary flow fault | ||
| E160 | Fan fault | ||
| E161 | Fan fault | ||
| E164 | Domestic hot water sensor error (In the ROI this is a heating flow switch error) | ||
| E167 | PCB fault | ||
| E168 | PCB lock out | ||
| E193 | Circulation | ||
| E270 | Dry fire | ||
| E317 | Wrong power supply (HZ) | ||
| E321 | Hot water thermistor fault | ||
| E384 | Flame detected when gas valve off (false flame) | ||
| E385 | Low voltage (less than 195v) |
Gas work stays with a Gas Safe registered engineer. Some codes only apply to a named range — check the model column.