| Fault code | Cause | Action (click on appropriate action) |
| 30 | Short circuit, boiler water temperature sensor | Check boiler water temperature sensor |
| 38 | Lead break, boiler water temperature sensor | Check boiler water temperature sensor |
| 51 | Short circuit, outlet temperature sensor | Check sensor |
| 52 | Short circuit, flow sensor | Check connections, lead & sensor |
| 59 | Lead break, outlet temperature sensor | Check sensor |
| 5 A | Lead break, flow sensor | Check connections, lead & sensor |
| b0 | Short circuit, flue gas temperature sensor | Check sensor |
| b8 | Lead break, flue gas temperature sensor | Check sensor |
| E3 | Fault in safety chain | Check the temperature limiter and connecting cables |
| E5 | Internal fault | Check the ionisation electrode and connecting cables |
| F0 | Internal fault | Control unit |
| F1 | Max. flue gas temperature exceeded | Check heating system fill level, circulation pump & system |
| F2 | Temperature limiter has responded | Check system fill level, pump & system. temperature limiter |
| F3 | Flame signal is present at burner start | Check ionisation electrode and connecting cable |
| F4 | No flame signal detected | Check ignition operation |
| F8 | Fuel valve closes too late | Check gas train, check both control paths |
| F9 | Fan speed too low during burner start | Check fan, cables and power supply to fan; check fan control |
| FA | Fan idle state not reached | Check fan, cables and power supply to fan; check fan control |
| FC | Electrical fan control (control unit) faulty | Check fan connecting cable, control unit |
| FD | Fault, burner control unit | Check ignition electrodes, cables, interference (EMC) field |
| FF | Fault, burner control unit | Check ignition electrodes, cables, interference (EMC) field |