| Fault codes | Meaning | Possible cause |
|---|---|---|
| F.00 | Fault: Flow temperature sensor | NTC plug not plugged in or has come loose, multiple plug on the PCB not plugged in correctly, interruption in cable harness, NTC sensor defective |
| F.01 | Fault: Return temperature sensor | NTC plug not plugged in or has come loose, multiple plug on the PCB not plugged in correctly, interruption in cable harness, NTC sensor defective |
| F.10 | Short circuit: Flow temperature sensor | NTC sensor defective, short circuit inthe cable harness, cable/casing |
| F.11 | Short circuit: Return temperature sensor | NTC sensor defective, short circuit in the cable harness, cable/casing |
| F.12 and F.91 | Short circuit: Cylinder temperature sensor | NTC sensor defective, short circuit in the cable harness, cable/casing |
| F.13 | Short circuit: Domestic hot water cylinder temperature sensor | NTC sensor defective, short circuit in the cable harness, cable/casing |
| F.20 | Safety switch-oft. Overheating temperature reached | Incorrect earth connection between cable harness and product, flow or return NTC defective (loose connection), black discharge viaignition cable, ignition plug or ignition electrode |
| F.22 | Safety switch-oft. Low water pressure in the boiler | No or insufficient water in the product, water pressure sensor defective, cable lo the pump or to the water pressure sensor loose/not connected/defective |
| F.23 | Safety switch-oft. Temperature difference too great (NTC1/NTC2) | Pump blocked, insufficient pump output, air in product, flow and return NTC sensoni connected the wrong way round |
| F.24 | Safety switch-oft. Temperature rise too fast | Pump blocked, insufficient pump output, air in product, system pressure too low, non-return valve blocked/incorrectly installed |
| F.25 | Safety switch-off. Flue gas temperature too high | Breakin plug connection for optional flue gas safety temperature limiter (STB), break in cable harness |
| F.27 | Safety switch-off. Fault in flame detection | Moisture on the electronics, electronics (flame monitor) defective. gas solenoid valve leaking |
| F.28 | Fault: Ignition unsuccessful when starting up | Gas meter defeclive or gas pressure monitor has triggered, air in gas, gas flow pressure too low, thermal isolator device (TAE) has triggered, incorrect gas restrictor,incorrect spare gas valve, fault on the gas valve, multiple plug on PCB incorrectly plugged in, break in cable harness,ignition system (ig- nition transformer, ignition cable, ignition plug, ignition electrode) defective, ionisation current interrupted (cable, electrode), incorrect earthing of product. electronics defective |
| F.29 | Fault: Flame loss | Gas supply temporarily stopped, flue gas recirculation, incorrect earthing of product, ignition transformer has spark fallure |
| F.32 | Fan frost protection function active: Fan speed outside the tolerance values | Plug on fan not correctly plugged in, multiple plug on PCB not correCUy plugged in, breakin cable harness, fan blocked, Hall sensor defective, electronlcs defective |
| F.33 | Fan frost protection function active: Air pressure switch fault | Pressure monitor has not switched or has switched at a fan speed value that is too high (insufficient air supply) Pressure monitor plug not correctly plugged in, pressure monitor defective, hose removed from between the pressure monitor and silencer, air/flue pipe blocked |
| FA9 | eBUS fault: Voltage too low | Short circuit on eBUS. eBUS overload or two power supplies with different polarities on the eBUS |
| F.61 | Fault: Gas valve control system | Short circuit/short to earth in cable harness for the gas valve, gas valve defective (colls shorted to earth), electronics defective |
| F.82 | Fault: Gas valve switch-off control | Delayed switch-off of gas valve, delayed extinguishing of flame signal,gas valve leaking, electronics defective |
| F.83 | Fault: EEPROM | Electronics defective |
| F.64 | Fault: Electronics/sensor/analogue-to-digital converter | Flow or return NTC short circuited, electronics defective |
| F.85 | Fault: Electronics temperature too high | Electronics overheating due to external influences, electronics defective |
| F.67 | Value sent back by ASIC is incorrect (flame slgnal) | Implausible flame signal, electronics defective |
| F.88 | Fault: Unstable flame (analogue input) | Air in gas, gas flow pressure too low, incorrect air ratio, incorrect gas restricter, ionisation flow interruption (cable, electrode) |
| F.70 | Invalid product code (DSN) | Display and PCB replaced alsame time and Device Specific Number not reset, wrong or missing output range coding resistance |
| F.71 | Fault: Flow/return temperature sensor | Flow temperature sensor signaling constant value: Flow temperature sensor incorrectly positioned on supply pipe, flow temperature sensor defective |
| F.72 | Fault: Deviation in the water pressure sensor/return temperature sensor | Flow/return NTC temperature difference too great -> flow and/or return temperature sensor defective |
| F.73 | Fault: Water pressure sensor not connected or has short-circuited | Interruption/short circuit of water pressure sensor, lntarrupaon/short circuit to GND in supply line to water pressure sensor or water pressure sensor defective |
| F.74 | Fault: Electrical problemin the water pressure sensor | Line to water pressure sensor has a short circuit to 5 V/24 V or internal fault in the water pressure sensor |
| F.75 | Fault: Pressure sensor | Pressure switch defective |
| F.78 | The safety cut-out in the primary heat exchanger is defective | Safety cut-out feedback does not match the gas valve feedback |
| F.77 | Fault: Condensate or smoke | No response, flue non-return flap defective |
| F.78 | Interruption to DHW outlet sensor at external controller | UK ink box is connected, but hot water NTC not bridged |
| F.83 | Fault: Burner temperature sensor | Burner temperature sensor is defective When the burner starts, the temperature change registered at the flow or retum temperature sensor is non-existent or too small: insufficient water in the product, the flow or retum temperature sensor is not in the correct position on the pipe |
| F.84 | Fault: Flow/return temperature sensor | Values not consistent, difference < -6 K Flow and return temperature sensors signalling implausible values: Flow and return temperature sensors have been inverted, flow and return temperature sensors have not been correctly Installed |
| F.85 | Fault: Temperature sensor | The flow and/or return temperature sensors have been installed on the same pipe/incorrect pipe Temperature sensor not connected or is connected incorrectly |
| F.88 | Fault: Underfloor heating contact | Underfloor heating contact open, sensor disconnected or defective |
| F.87 | Fault: Electrodes | Electrodes not connected or they are connected incorrectly, short circuit in the cable harness |
| F.88 | Fault: Gas valve | Gas valve not connected or it is connected incorrecUy, short circuit in the cable harness |
| F.89 | Fault: Pump | Pump not connected or it is connected incorrectly, incorrect pump connected, short circuit in the cable harness |
| Connection | No communication between the PCB and the user interface | Electronics defective |