ATAG Combi Boiler Error Codes When your ATAG boiler has an error, you will see an error symbol like the one above. This symbol is normally accompanied by one of the codes in the tables below. The ATAG Regular Boiler Error Codes are a series of numerical codes that are displayed by your boiler if you find fault with one of its components. You can use this list to identify the component causing the problem.
ATAG Boiler Error Code Solutions
| Fault Code | System Behaviour |
| 10 | Outside sensor error |
| 20 | Flow sensor error |
| 40 | Return sensor error |
| 61 | Bus communication error |
| 78 | Water pressure out of range |
| 105 | Venting program active when power turn on/ interrupted (runs for 7 mins) |
| 110 | Exceeded safety temperature |
| 111 | Exceeded maximum pressure |
| 119 | X2 link positions 4 and 5 are missing |
| 129 | Fan doesn’t start |
| 133 | No flame after 5 ignition attempts |
| 151 | Fan error or control unit defective (speed control is not achieved) |
| 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 |
| 1P4 | Pressure needs filling to 0.5 – 0.8 bar |
| 109 | Pressure > Pmax error |
| 110 | Send probe damaged |
| 112 | Return probe error – could be damaged |
| 114 | Outdoor sensor error – could be damaged |
| 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 occurred |
| 501 | No flame detected |
| 612 | Fan fault – fan isn’t starting up |
iC & iS Combi Boiler Error Codes
| Fault Code | System Behaviour |
| 50 | Domestic hot water (DHW) sensor error |
| 117 | Pressure greater than 3 bar or pump pressure increase is too high |
| 118 | Pressure less than 1 bar or pump pressure increase too low (no pump detection) |
ATAG Error code 133
If you are seeing the error code 133, your boiler’s flame is failing after 5 ignition attempts. This could be down to your condensate pipe freezing.