| Code | Meaning | Models |
|---|---|---|
| 10 | Outside sensor error | |
| 20 | Flow sensor error | |
| 40 | Return sensor error | |
| 50 | Domestic hot water (DHW) sensor error | IC, IS |
| 61 | Bus communication error | |
| 78 | Water pressure out of range | |
| 105 | Venting program active when power turned on / interrupted (runs for 7 mins)Ê | |
| 110 | Exceeded safety temperature | |
| 111 | Exceeded maximum pressure | |
| 119 | X2 link position 4 and 5 missing | |
| 129 | Fan doesnÕt start | |
| 133 | No flame after 5 ignition attempts | |
| 151 | Fan error or control unit defective (speed control is not achieved)Ê | |
| 154 | Return greater than flow – flow temperature increases too fast | |
| 101 | Overheat error | |
| 102 | Pressure sensor fault | |
| 104 | Flow check failed | |
| 108 | Pressure needs filling to < 0.5 bar | |
| 1P4 | Pressure needs filling to 0.5 – 0.8 bar | |
| 109 | Pressure > Pmax error | |
| 110 | Send probe damaged | |
| 112 | Return probe error – could be damanged | |
| 114 | Outdoor sensor error – could be damaged | |
| 117 | Pressure greater than 3 bar or pump pressure increase is too high | IC, IS |
| 118 | Pressure less than 1 bar or pump pressure increase too low (no pump detection). | IC, IS |
| 133 | No flame after 5ÊignitionÊattempts | |
| 141 | Central heating flow switch is open | |
| 201 | Domestic hot water (DHW) probe damaged | |
| 203 | Tank probe damaged | |
| 303 | Printed circuit board (PCB) error | |
| 304 | Too many resets have occured | |
| 501 | No flame detected | |
| 612 | Fan fault – fan isnÕt starting up |
Gas work stays with a Gas Safe registered engineer. Some codes only apply to a named range — check the model column.