| A 41 | Fan error (flue gas extractor fault). | If the extractor/fan does not start or its tachometer/Hall does not deliver pulses, the PCB detects a fan fault. Check 230 V to the motor and rpm/tach signal at the connector; if there is no rotation or no pulses, the extractor is the cause. |
| E 23 | Fan speed too low. | Worn or blocked extractor rotates below the threshold and the PCB detects it as low speed. Check that the fan reaches nominal rpm (Hall pulses) and that there are no frictions; if it does not increase rpm, replace the extractor. |
| 6 01 | Flue gas expulsion fault (obstruction or fan fault). | If the extractor does not move flow or does not reach speed, the flue gas evacuation fails and the boiler locks with 6 01. Check the fan rotation and the closure of the flue gas pressure switch; if the fan does not start or does not provide flow, it is the cause. |
| 6 04 | Insufficient fan speed. | The extractor rotates below the target value (worn winding, bearings, dirt) and the electronics detect it as insufficient speed. Measure power supply and Hall signal; if the fan does not reach the specified rpm, replace it. |
| 6 12 | Incorrect fan speed measurement (fan fault/signal). | Tachometer/Hall fault of the fan or unstable rotation causes invalid rpm reading and lockout. Check Hall pulses at the connector and rpm stability; if there is no signal or it fluctuates, the fan is the cause. |