Ferroli is an Italian heating manufacturer with over 60 years of experience, founded in Verona in 1955. Their boilers are well-regarded for quality engineering and are popular across Europe. Ferroli fault codes use an ‘A’ prefix for lockout faults and ‘F’ for blocking/warning codes.
Ferroli Boiler Fault Codes
All Ferroli Fault Codes 90
| Code | Fault | Severity | Type | View guide |
|---|---|---|---|---|
| A01 | Ignition Failure / No Flame The boiler has failed to ignite — no flame was detected after the ignition sequence.… | Medium | DIY Check | View Guide |
| A02 | Flame Loss During Operation The boiler ignited but then lost its flame during normal operation. Common causes include gas… | Medium | DIY Check | View Guide |
| A03 | Safety Thermostat Lockout The boiler safety thermostat has triggered due to overheating. | High | Engineer | View Guide |
| A04 | False Ionisation / Flame Detected Without Demand The boiler's ionisation circuit is detecting a flame when none should be present. A serious… | High | Engineer | View Guide |
| A05 | Overheat Lockout The safety thermostat has detected excessively high temperatures and shut the boiler down. | High | Engineer | View Guide |
| A06 | Overheat Lockout — Secondary A secondary overheat safety device has activated. | High | Engineer | View Guide |
| A07 | Fan Fault The fan is not operating at the required speed or has stopped. | High | Engineer | View Guide |
| A08 | Fan Overspeed The fan is running above its rated maximum speed. | High | Engineer | View Guide |
| A09 | Fan Not Responding to Start Command The fan has not started within the required time after the PCB sent the start… | High | Engineer | View Guide |
| A10 | Flow NTC Open Circuit The flow temperature sensor circuit is broken. | Medium | Engineer | View Guide |
| A11 | Return NTC Open Circuit The return temperature sensor circuit is broken. | Medium | Engineer | View Guide |
| A12 | DHW NTC Short Circuit The hot water sensor wiring has shorted. | Medium | Engineer | View Guide |
| A13 | Flow NTC Sensor Fault The flow temperature sensor has failed or has a wiring fault. | Medium | Engineer | View Guide |
| A14 | Return NTC Sensor Fault The return temperature sensor has failed or has a wiring fault. | Medium | Engineer | View Guide |
| A15 | DHW Outlet Sensor Fault The domestic hot water outlet temperature sensor has failed or has a wiring issue. | Medium | Engineer | View Guide |
| A16 | Gas Valve Lockout — Failed to Close The gas valve has failed to close correctly after the burner should have stopped. Safety-critical. | High | Engineer | View Guide |
| A17 | Gas Valve Fault The gas valve is not responding to commands. | High | Engineer | View Guide |
| A18 | PCB Fault Internal error on the printed circuit board. | High | Engineer | View Guide |
| A19 | PCB Fault — Communication Error An internal communication error has been detected on the PCB. | High | Engineer | View Guide |
| A20 | Condensate Siphon Blocked The internal condensate siphon is blocked with scale, debris, or ice. | Medium | Engineer | View Guide |
| A21 | Flue Temperature Too High Flue gas temperature has exceeded the limit. | High | Engineer | View Guide |
| A22 | Low Gas Pressure Insufficient gas supply pressure detected. | High | Engineer | View Guide |
| A23 | Pump Fault The pump is not operating correctly. | High | Engineer | View Guide |
| A24 | Pump Over-Speed The pump is running faster than expected. | Medium | Engineer | View Guide |
| A25 | Three-Way Valve Fault The diverter valve is not switching. | Medium | Engineer | View Guide |
| A26 | Condensate Blocked The condensate drain is blocked or frozen. | Medium | DIY Check | View Guide |
| A27 | PCB Fault The main PCB has detected an internal fault. | High | Engineer | View Guide |
| A28 | Flame Instability The flame signal is fluctuating. | High | Engineer | View Guide |
| A29 | Fan Fault The fan is not running correctly. | High | Engineer | View Guide |
| A30 | Air Pressure Switch Fault The APS is not detecting correct airflow. | High | Engineer | View Guide |
| A31 | Flow/Return Sensor Reversed The sensors are fitted to the wrong pipes. | Medium | Engineer | View Guide |
| A61 | PCB AGC01 Internal Error On Ferroli Bluehelix Tech boilers, A61 indicates an internal error in the main PCB (AGC01… | High | Engineer | View Guide |
| A62 | No Communication Between PCB and Gas Valve On Ferroli boilers, A62 indicates there is no communication between the main PCB and the… | High | Engineer | View Guide |
| A64 | Maximum Consecutive Resets Exceeded On Ferroli Bluehelix Tech boilers, A64 means the maximum number of consecutive resets has been… | High | Engineer | View Guide |
| D1 | Diverter Valve Fault The diverter valve (which switches water flow between heating and hot water) appears to not… | Medium | Engineer | View Guide |
| F01 | Low Water Pressure Warning A warning (non-lockout) version of the low pressure fault on some Ferroli models. The boiler… | Low | DIY Check | View Guide |
| F02 | Overheat Lockout The boiler exceeded its safe temperature. | High | Engineer | View Guide |
| F03 | Low Water Pressure (Warning) System pressure is approaching the minimum — a warning before lockout occurs. | Low | DIY Check | View Guide |
| F04 | Ionisation Fault No flame detected during ignition. | High | Engineer | View Guide |
| F05 | Air Pressure Switch Error The air pressure switch is not registering correctly — this switch confirms the fan has… | High | Engineer | View Guide |
| F06 | Flue Sensor Fault The flue gas NTC sensor is faulty. | Medium | Engineer | View Guide |
| F07 | High Flue Gas Temperature The flue gas probe (exchanger probe) has detected an excessively high temperature for more than… | High | Engineer | View Guide |
| F08 | Overtemperature Protection — Flow Sensor On Ferroli Bluehelix Tech boilers, F08 indicates the overtemperature protection has activated based on the… | High | Engineer | View Guide |
| F09 | Overtemperature Protection — Return Sensor On Ferroli Bluehelix Tech boilers, F09 indicates the overtemperature protection has activated based on the… | High | Engineer | View Guide |
| F10 | Flue Temperature Too High The flue gas temperature sensor has detected temperatures above safe limits. | High | Engineer | View Guide |
| F11 | Return Sensor Fault On Ferroli boilers, F11 indicates the return temperature sensor has a wiring fault (shorted or… | Medium | Engineer | View Guide |
| F12 | DHW Sensor Fault The domestic hot water temperature sensor has a wiring fault (shorted or disconnected) or has… | Medium | Engineer | View Guide |
| F13 | Flue Probe Fault On Ferroli boilers, F13 indicates the flue gas probe has a wiring fault (shorted or… | Medium | Engineer | View Guide |
| F14 | Flow Sensor 2 / Fan Problem Fault On some Ferroli models, F14 indicates either a secondary delivery sensor fault (DOMIcondens) or a… | Medium | Engineer | View Guide |
| F15 | Supply Voltage Low (Modena HE) On Ferroli Modena HE combi boilers, F15 indicates the supply voltage has dropped below 170V. | Medium | Engineer | View Guide |
| F16 | Low Water Pressure System pressure is below minimum. | Low | DIY Check | View Guide |
| F17 | No Water Circulation The pump is not circulating water. | High | Engineer | View Guide |
| F18 | Rapid Temperature Rise Flow temperature rising too fast. | High | Engineer | View Guide |
| F20 | DHW NTC Open Circuit The hot water sensor circuit is broken. | Medium | Engineer | View Guide |
| F21 | Outdoor Sensor Fault The outdoor sensor is faulty or disconnected. | Low | Engineer | View Guide |
| F22 | Low Water Pressure (Pressure Switch) The pressure switch has detected dangerously low pressure. | Medium | Engineer | View Guide |
| F23 | Flow/Return Differential Too Large The temperature gap is too high. | Medium | Engineer | View Guide |
| F24 | Frost Protection Active Frost protection cycles are running. | Medium | DIY Check | View Guide |
| F25 | PCB EEPROM Error The PCB memory is corrupted. | High | Engineer | View Guide |
| F26 | Gas Valve Relay Fault The PCB relay controlling the gas valve has failed. | High | Engineer | View Guide |
| F27 | Flame Detected After Shutdown A flame signal is present after the gas valve should be closed. | High | Engineer | View Guide |
| F28 | Flame Loss (Condensate Related) Flame loss associated with a blocked or frozen condensate pipe — Ferroli uses F28 specifically… | Medium | DIY Check | View Guide |
| F29 | Ignition Electrode Worn The ignition electrode spark is weak. | High | Engineer | View Guide |
| F30 | External Thermostat Fault The external thermostat signal is incorrect. | Medium | Engineer | View Guide |
| F31 | eBUS Communication Fault The eBUS communication line has failed. | Medium | Engineer | View Guide |
| F32 | Mains Voltage Error Mains supply voltage is outside range. | Medium | Engineer | View Guide |
| F33 | Combustion Quality Fault Air/gas mixture is outside limits. | High | Engineer | View Guide |
| F34 | Low Supply Voltage On Ferroli boilers, F34 indicates the mains supply voltage has dropped below 170V — too… | Medium | Engineer | View Guide |
| F35 | Incorrect Mains Frequency On Ferroli boilers, F35 indicates an incorrect or irregular mains power frequency (should be 50Hz… | Medium | Engineer | View Guide |
| F36 | Return NTC Short Circuit The return sensor wiring has shorted. | Medium | Engineer | View Guide |
| F37 | Low Water Pressure The system water pressure has dropped below the minimum required level. | Low | DIY Check | View Guide |
| F38 | Flow NTC Short Circuit The flow sensor wiring has shorted. | Medium | Engineer | View Guide |
| F39 | External Temperature Probe Fault The optional external temperature probe (for weather compensation) has a wiring fault or has been… | Low | Engineer | View Guide |
| F40 | Pressure Sensor Fault The electronic pressure sensor gives wrong readings. | Medium | Engineer | View Guide |
| F41 | Maximum Delta-T Protection Activated On Ferroli Bluehelix Tech boilers, F41 indicates the maximum allowable temperature difference between flow and… | High | Engineer | View Guide |
| F42 | Sensor Control Protection Activated On Ferroli Bluehelix Tech, F42 indicates the sensor control protection has activated due to heating… | High | Engineer | View Guide |
| F43 | Heat Exchanger Protection — No Circulation On Ferroli boilers, F43 indicates the heat exchanger protection has activated due to no water… | High | Engineer | View Guide |
| F44 | Cylinder Sensor Fault The cylinder NTC is faulty (system boilers). | Medium | Engineer | View Guide |
| F45 | Coding Plug Missing The boiler coding plug is missing. | High | Engineer | View Guide |
| F46 | Phase/Neutral Reversed The electrical supply has reversed polarity. | High | Engineer | View Guide |
| F47 | Pump Stuck The pump has seized. | High | Engineer | View Guide |
| F48 | DHW Flow Switch Fault The DHW flow switch is not detecting water flow. | Medium | Engineer | View Guide |
| F49 | Pump Over-Run Fault The pump did not stop after the burner shut down. | Medium | Engineer | View Guide |
| F50 | Diverter Valve Timeout The diverter did not switch in time. | Medium | Engineer | View Guide |
| F51 | Flame Signal Too Weak The ionisation current is below minimum. | High | Engineer | View Guide |
| F52 | Controller Internal Error On Ferroli Modena HE combi boilers, F52 indicates the controller has an internal error. | High | Engineer | View Guide |
| F53 | Fan Speed Error Fan speed out of range. | High | Engineer | View Guide |
| F54 | Gas Valve Step Error The gas valve stepper motor is not responding. | High | Engineer | View Guide |
| F55 | Room Controller Lost Communication with the room controller is lost. | Low | Engineer | View Guide |
| F56 | Calibration Error / Incomplete Calibration On Ferroli Bluehelix Tech boilers, F56 indicates the auto-calibration procedure did not complete correctly, or… | Medium | Engineer | View Guide |