Brand Specific Information
You can search by fault code or model. Please also note some fault codes will be very similar to Vaillant models as they share similar or identical electronics for some models. Scroll down for tables showing different models.
The Following table is applicable for the following models
- Energy
| Fault codes | Repair | Meaning | Possible cause | Model |
|---|---|---|---|---|
| F.00 | Link | 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 | Energy |
| F.01 | Link | 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 | Energy |
| F.10 | Link | Short circuit: Flow temperature sensor | NTC sensor defective, short circuit inthe cable harness, cable/casing | Energy |
| F.11 | Link | Short circuit: Return temperature sensor | NTC sensor defective, short circuit in the cable harness, cable/casing | Energy |
| F.12 and F.91 | Link | Short circuit: Cylinder temperature sensor | NTC sensor defective, short circuit in the cable harness, cable/casing | Energy |
| F.13 | Link | Short circuit: Domestic hot water cylinder temperature sensor | NTC sensor defective, short circuit in the cable harness, cable/casing | Energy |
| F.20 | Link | 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 | Energy |
| F.22 | Link | 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 | Energy |
| F.23 | Link | 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 | Energy |
| F.24 | Link | 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 | Energy |
| F.25 | Link | Safety switch-off. Flue gas temperature too high | Breakin plug connection for optional flue gas safety temperature limiter (STB), break in cable harness | Energy |
| F.27 | Link | Safety switch-off. Fault in flame detection | Moisture on the electronics, electronics (flame monitor) defective. gas solenoid valve leaking | Energy |
| F.28 | Link | 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 | Energy |
| F.29 | Link | Fault: Flame loss | Gas supply temporarily stopped, flue gas recirculation, incorrect earthing of product, ignition transformer has spark fallure | Energy |
| F.32 | Link | 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 | Energy |
| F.33 | Link | 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 | Energy |
| FA9 | Link | eBUS fault: Voltage too low | Short circuit on eBUS. eBUS overload or two power supplies with different polarities on the eBUS | Energy |
| F.61 | Link | 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 | Energy |
| F.82 | Link | Fault: Gas valve switch-off control | Delayed switch-off of gas valve, delayed extinguishing of flame signal,gas valve leaking, electronics defective | Energy |
| F.83 | Link | Fault: EEPROM | Electronics defective | Energy |
| F.64 | Link | Fault: Electronics/sensor/analogue-to-digital converter | Flow or return NTC short circuited, electronics defective | Energy |
| F.85 | Link | Fault: Electronics temperature too high | Electronics overheating due to external influences, electronics defective | Energy |
| F.67 | Link | Value sent back by ASIC is incorrect (flame slgnal) | Implausible flame signal, electronics defective | Energy |
| F.88 | Link | Fault: Unstable flame (analogue input) | Air in gas, gas flow pressure too low, incorrect air ratio, incorrect gas restricter, ionisation flow interruption (cable, electrode) | Energy |
| F.70 | Link | Invalid product code (DSN) | Display and PCB replaced alsame time and Device Specific Number not reset, wrong or missing output range coding resistance | Energy |
| F.71 | Link | Fault: Flow/return temperature sensor | Flow temperature sensor signaling constant value: Flow temperature sensor incorrectly positioned on supply pipe, flow temperature sensor defective | Energy |
| F.72 | Link | Fault: Deviation in the water pressure sensor/return temperature sensor | Flow/return NTC temperature difference too great -> flow and/or return temperature sensor defective | Energy |
| F.73 | Link | 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 | Energy |
| F.74 | Link | 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 | Energy |
| F.75 | Link | Fault: Pressure sensor | Pressure switch defective | Energy |
| F.78 | Link | The safety cut-out in the primary heat exchanger is defective | Safety cut-out feedback does not match the gas valve feedback | Energy |
| F.77 | Link | Fault: Condensate or smoke | No response, flue non-return flap defective | Energy |
| F.78 | Link | Interruption to DHW outlet sensor at external controller | UK ink box is connected, but hot water NTC not bridged | Energy |
| F.83 | Link | 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 | Energy |
| F.84 | Link | 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 | Energy |
| F.85 | Link | 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 | Energy |
| F.88 | Link | Fault: Underfloor heating contact | Underfloor heating contact open, sensor disconnected or defective | Energy |
| F.87 | Link | Fault: Electrodes | Electrodes not connected or they are connected incorrectly, short circuit in the cable harness | Energy |
| F.88 | Link | Fault: Gas valve | Gas valve not connected or it is connected incorrecUy, short circuit in the cable harness | Energy |
| F.89 | Link | Fault: Pump | Pump not connected or it is connected incorrectly, incorrect pump connected, short circuit in the cable harness | Energy |
| Connection | Link | No communication between the PCB and the user interface | Electronics defective | Energy |
The Following table is applicable for the following models
- Ultracomâ‚‚ sxi,
- Ultracomâ‚‚ cxi
- Ultracomâ‚‚ 35 store
- Betacom a
- Xtrafast 96/120
- Xtrafast 96/120E1
| Codes | Repair | Description | Model | |
|---|---|---|---|---|
| Err | Link | User interface fault | Ultracom sxi | ` |
| Err | Link | User interface fault | Ultracom cxi | |
| Err | Link | User interface fault | Ultracom 35 store | |
| Err | Link | User interface fault | Betacom a | |
| F00 | Link | No fault | Xtrafast 96/120E1 | |
| F00 | Link | No fault | Xtrafast 96/120 | |
| F00 | Link | Flow heating temperature sensor fault | Ultracom sxi | |
| F00 | Link | Flow heating temperature sensor fault | Ultracom cxi | |
| F00 | Link | Flow heating temperature sensor fault | Ultracom 35 store | |
| F00 | Link | Flow heating temperature sensor fault | Betacom a | |
| F01 | Link | Return heating temperature sensor fault | Ultracom sxi | |
| F01 | Link | Return heating temperature sensor fault | Ultracom cxi | |
| F01 | Link | Return heating temperature sensor fault | Ultracom 35 store | |
| F01 | Link | Return heating temperature sensor fault | Betacom a | |
| F02 | Link | Air flow fault | Xtrafast 96/120E1 | |
| F02 | Link | Air flow fault | Xtrafast 96/120 | |
| F02 | Link | Hot water temperature sensor fault | Ultracom 35 store | |
| F03 | Link | Storage tank temperature sensor fault | Ultracom 35 store | |
| F04 | Link | Ignition fault - flame detection | Xtrafast 96/120E1 | |
| F04 | Link | Ignition fault - flame detection | Xtrafast 96/120 | |
| F05 | Link | Overheating | Xtrafast 96/120E1 | |
| F05 | Link | Overheating | Xtrafast 96/120 | |
| F06 | Link | Central heating thermistor/wiring fault | Xtrafast 96/120E1 | |
| F06 | Link | Central heating thermistor/wiring fault | Xtrafast 96/120 | |
| F07 | Link | Domestic hot water thermistor/wiring fault | Xtrafast 96/120E1 | |
| F07 | Link | Domestic hot water thermistor/wiring fault | Xtrafast 96/120 | |
| F08 | Link | Storage vessel thermistor/wiring fault | Xtrafast 96/120E1 | |
| F08 | Link | Storage vessel thermistor/wiring fault | Xtrafast 96/120 | |
| F09 | Link | System pressure sensor fault | Xtrafast 96/120E1 | |
| F09 | Link | System pressure sensor fault | Xtrafast 96/120 | |
| F10 | Link | Fan fault | Xtrafast 96/120E1 | |
| F10 | Link | Fan fault | Xtrafast 96/120 | |
| F10 | Link | Flow heating temperature sensor fault | Ultracom sxi | |
| F10 | Link | Flow heating temperature sensor fault | Ultracom cxi | |
| F10 | Link | Flow heating temperature sensor fault | Ultracom 35 store | |
| F10 | Link | Flow heating temperature sensor fault | Betacom a | |
| F11 | Link | Poor circulation | Xtrafast 96/120E1 | |
| F11 | Link | Poor circulation | Xtrafast 96/120 | |
| F11 | Link | Return heating temperature sensor fault | Ultracom sxi | |
| F11 | Link | Return heating temperature sensor fault | Ultracom cxi | |
| F11 | Link | Return heating temperature sensor fault | Ultracom 35 store | |
| F11 | Link | Return heating temperature sensor fault | Betacom a | |
| F12 | Link | User interface fault | Xtrafast 96/120E1 | |
| F12 | Link | User interface fault | Xtrafast 96/120 | |
| F12 | Link | Hot water temperature sensor fault | Ultracom 35 store | |
| F13 | Link | Main pcb fault | Xtrafast 96/120E1 | |
| F13 | Link | Main pcb fault | Xtrafast 96/120 | |
| F13 | Link | Storage tank temperature sensor fault | Ultracom 35 store | |
| F14 | Link | Central heating flow temperature > 97 degrees | Xtrafast 96/120E1 | |
| F14 | Link | Central heating flow temperature > 97 degrees | Xtrafast 96/120 | |
| F15 | Link | Gas mechanism fault | Xtrafast 96/120E1 | |
| F15 | Link | Gas mechanism fault | Xtrafast 96/120 | |
| F20 | Link | Communication fault | Xtrafast 96/120E1 | |
| F20 | Link | Communication fault | Xtrafast 96/120 | |
| F20 | Link | Overheating fault | Ultracom sxi | |
| F20 | Link | Overheating fault | Ultracom cxi | |
| F20 | Link | Overheating fault | Ultracom 35 store | |
| F20 | Link | Overheating fault | Betacom a | |
| F22 | Link | Low water pressure | Ultracom sxi | |
| F22 | Link | Low water pressure | Ultracom cxi | |
| F22 | Link | Low water pressure | Ultracom 35 store | |
| F22 | Link | Low water pressure | Betacom a | |
| F23 | Link | Water circulation fault | Ultracom sxi | |
| F23 | Link | Water circulation fault | Ultracom cxi | |
| F23 | Link | Water circulation fault | Ultracom 35 store | |
| F23 | Link | Water circulation fault | Betacom a | |
| F24 | Link | Water circulation fault | Ultracom sxi | |
| F24 | Link | Water circulation fault | Ultracom cxi | |
| F24 | Link | Water circulation fault | Ultracom 35 store | |
| F24 | Link | Water circulation fault | Betacom a | |
| F26 | Link | Fault in gas valve | Ultracom sxi | |
| F26 | Link | Fault in gas valve | Ultracom cxi | |
| F26 | Link | Fault in gas valve | Ultracom 35 store | |
| F26 | Link | Fault in gas valve | Betacom a | |
| F27 | Link | Flame detection fault | Ultracom sxi | |
| F27 | Link | Flame detection fault | Ultracom cxi | |
| F27 | Link | Flame detection fault | Ultracom 35 store | |
| F27 | Link | Flame detection fault | Betacom a | |
| F28 | Link | Ignition fault | Ultracom sxi | |
| F28 | Link | Ignition fault | Ultracom cxi | |
| F28 | Link | Ignition fault | Ultracom 35 store | |
| F28 | Link | Ignition fault | Betacom a | |
| F29 | Link | Loss of flame during operation | Ultracom sxi | |
| F29 | Link | Loss of flame during operation | Ultracom cxi | |
| F29 | Link | Loss of flame during operation | Ultracom 35 store | |
| F29 | Link | Loss of flame during operation | Betacom a | |
| F32 | Link | Incorrect air pressure | Ultracom sxi | |
| F32 | Link | Incorrect air pressure | Ultracom cxi | |
| F32 | Link | Incorrect air pressure | Ultracom 35 store | |
| F32 | Link | Incorrect air pressure | Betacom a | |
| F49 | Link | EBUS voltage fault | Ultracom sxi | |
| F49 | Link | EBUS voltage fault | Ultracom cxi | |
| F49 | Link | EBUS voltage fault | Ultracom 35 store | |
| F49 | Link | EBUS voltage fault | Betacom a | |
| F61 | Link | Fault in the main board | Ultracom sxi | |
| F61 | Link | Fault in the main board | Ultracom cxi | |
| F61 | Link | Fault in the main board | Ultracom 35 store | |
| F61 | Link | Fault in the main board | Betacom a | |
| F62 | Link | Fault in the main board | Ultracom sxi | |
| F62 | Link | Fault in the main board | Ultracom cxi | |
| F62 | Link | Fault in the main board | Ultracom 35 store | |
| F62 | Link | Fault in the main board | Betacom a | |
| F63 | Link | Fault in the main board | Ultracom sxi | |
| F63 | Link | Fault in the main board | Ultracom cxi | |
| F63 | Link | Fault in the main board | Ultracom 35 store | |
| F63 | Link | Fault in the main board | Betacom a | |
| F64 | Link | Fault in the main board | Ultracom sxi | |
| F64 | Link | Fault in the main board | Ultracom cxi | |
| F64 | Link | Fault in the main board | Ultracom 35 store | |
| F64 | Link | Fault in the main board | Betacom a | |
| F65 | Link | Fault in the main board | Ultracom sxi | |
| F65 | Link | Fault in the main board | Ultracom cxi | |
| F65 | Link | Fault in the main board | Ultracom 35 store | |
| F65 | Link | Fault in the main board | Betacom a | |
| F67 | Link | Fault in the main board | Ultracom sxi | |
| F67 | Link | Fault in the main board | Ultracom cxi | |
| F67 | Link | Fault in the main board | Ultracom 35 store | |
| F67 | Link | Fault in the main board | Betacom a | |
| F68 | Link | Fluctuation of flame signal | Ultracom sxi | |
| F68 | Link | Fluctuation of flame signal | Ultracom cxi | |
| F68 | Link | Fluctuation of flame signal | Ultracom 35 store | |
| F68 | Link | Fluctuation of flame signal | Betacom a | |
| F70 | Link | User interface incompatible with the main board | Ultracom sxi | |
| F70 | Link | User interface incompatible with the main board | Ultracom cxi | |
| F70 | Link | User interface incompatible with the main board | Ultracom 35 store | |
| F70 | Link | User interface incompatible with the main board | Betacom a | |
| F71 | Link | Flow heating temperature sensor fault | Ultracom sxi | |
| F71 | Link | Flow heating temperature sensor fault | Ultracom cxi | |
| F71 | Link | Flow heating temperature sensor fault | Ultracom 35 store | |
| F71 | Link | Flow heating temperature sensor fault | Betacom a | |
| F72 | Link | Permanent temperature difference between flow and return heating sensors | Ultracom sxi | |
| F72 | Link | Permanent temperature difference between flow and return heating sensors | Ultracom cxi | |
| F72 | Link | Permanent temperature difference between flow and return heating sensors | Ultracom 35 store | |
| F72 | Link | Permanent temperature difference between flow and return heating sensors | Betacom a | |
| F73 | Link | Heating circuit pressure sensor fault | Ultracom sxi | |
| F73 | Link | Heating circuit pressure sensor fault | Ultracom cxi | |
| F73 | Link | Heating circuit pressure sensor fault | Ultracom 35 store | |
| F73 | Link | Heating circuit pressure sensor fault | Betacom a | |
| F74 | Link | Heating circuit pressure sensor fault | Ultracom sxi | |
| F74 | Link | Heating circuit pressure sensor fault | Ultracom cxi | |
| F74 | Link | Heating circuit pressure sensor fault | Ultracom 35 store | |
| F74 | Link | Heating circuit pressure sensor fault | Betacom a | |
| F76 | Link | Thermal fuse fault | Ultracom sxi | |
| F76 | Link | Thermal fuse fault | Ultracom cxi | |
| F76 | Link | Thermal fuse fault | Ultracom 35 store | |
| F76 | Link | Thermal fuse fault | Betacom a | |
| F77 | Link | Fault in gas valve motor | Ultracom sxi | |
| F77 | Link | Fault in gas valve motor | Ultracom cxi | |
| F77 | Link | Fault in gas valve motor | Ultracom 35 store | |
| F77 | Link | Fault in gas valve motor | Betacom a | |
| F79 | Link | Storage tank temperature sensor fault | Ultracom 35 store | |
| F81 | Link | Overheating of hot water circuit | Ultracom 35 store | |
| F83 | Link | No water in the installation | Ultracom sxi | |
| F83 | Link | No water in the installation | Ultracom cxi | |
| F83 | Link | No water in the installation | Ultracom 35 store | |
| F83 | Link | No water in the installation | Betacom a | |
| F84 | Link | Permanent temperature difference between flow and return heating sensors | Ultracom sxi | |
| F84 | Link | Permanent temperature difference between flow and return heating sensors | Ultracom cxi | |
| F84 | Link | Permanent temperature difference between flow and return heating sensors | Ultracom 35 store | |
| F84 | Link | Permanent temperature difference between flow and return heating sensors | Betacom a | |
| F85 | Link | Flow and Return heating sensor fault | Ultracom sxi | |
| F85 | Link | Flow and Return heating sensor fault | Ultracom cxi | |
| F85 | Link | Flow and Return heating sensor fault | Ultracom 35 store | |
| F85 | Link | Flow and Return heating sensor fault | Betacom a | |
| F86 | Link | Underfloor heating contact fault | Ultracom sxi | |
| F86 | Link | Underfloor heating contact fault | Ultracom cxi | |
| F86 | Link | Underfloor heating contact fault | Ultracom 35 store | |
| F86 | Link | Underfloor heating contact fault | Betacom a |
The Following table is applicable for the following models
- Xtramax HE
- Ultrapower sxi
- Ultracom sxi
- Ultracom hxi
- Ultracom cx
- Ultracom cxi
- sxi
- SI
- hxi f
- lexicom sx
- flexicom hx
- flexicom cx
- cxi
- CI
- Plus CI
| Codes | Description | Model | |
|---|---|---|---|
| F1 | Link | Ignition fault | Xtramax HE |
| F1 | Link | Ignition fault | Ultrapower sxi |
| F1 | Link | Ignition fault | Ultracom sxi |
| F1 | Link | Ignition fault | Ultracom hxi |
| F1 | Link | Ignition fault | Ultracom cx |
| F1 | Link | Ignition fault | Ultracom cxi |
| F1 | Link | Ignition fault | sxi |
| F1 | Link | Ignition fault | SI |
| F1 | Link | Ignition fault | hxi |
| F1 | Link | Ignition fault | flexicom sx |
| F1 | Link | Ignition fault | flexicom hx |
| F1 | Link | Ignition fault | flexicom cx |
| F1 | Link | Ignition fault | cxi |
| F1 | Link | Ignition fault | CI Plus |
| F1 | Link | Ignition fault | CI |
| F10 | Link | Central return flow thermistor | Xtramax HE |
| F10 | Link | Central return flow thermistor | Ultrapower sxi |
| F10 | Link | Central return flow thermistor | Ultracom sxi |
| F10 | Link | Central return flow thermistor | Ultracom hxi |
| F10 | Link | Central return flow thermistor | Ultracom cx |
| F10 | Link | Central return flow thermistor | Ultracom cxi |
| F10 | Link | Central return flow thermistor | sxi |
| F10 | Link | Central return flow thermistor | SI |
| F10 | Link | Central return flow thermistor | hxi |
| F10 | Link | Central return flow thermistor | flexicom sx |
| F10 | Link | Central return flow thermistor | flexicom hx |
| F10 | Link | Central return flow thermistor | flexicom cx |
| F10 | Link | Central return flow thermistor | cxi |
| F10 | Link | Central return flow thermistor | CI Plus |
| F10 | Link | Central return flow thermistor | CI |
| F11 | Link | Main board connection fault | Xtramax HE |
| F11 | Link | Main board connection fault | Ultrapower sxi |
| F11 | Link | Main board connection fault | Ultracom sxi |
| F11 | Link | Main board connection fault | Ultracom hxi |
| F11 | Link | Main board connection fault | Ultracom cx |
| F11 | Link | Main board connection fault | Ultracom cxi |
| F11 | Link | Main board connection fault | sxi |
| F11 | Link | Main board connection fault | SI |
| F11 | Link | Main board connection fault | hxi |
| F11 | Link | Flow and or return thermistor fault | flexicom sx |
| F11 | Link | Flow and or return thermistor fault | flexicom hx |
| F11 | Link | Flow and or return thermistor fault | flexicom cx |
| F11 | Link | Main board connection fault | cxi |
| F11 | Link | Main board connection fault | CI Plus |
| F11 | Link | Main board connection fault | CI |
| F12 | Link | User interface connection fault | Xtramax HE |
| F12 | Link | Connection fault between main pcb and display pcb | sxi |
| F12 | Link | Connection fault between main pcb and display pcb | SI |
| F12 | Link | Connection fault between main pcb and display pcb | hxi |
| F12 | Link | Connection fault between main pcb and display pcb | cxi |
| F12 | Link | Connection fault between main pcb and display pcb | CI Plus |
| F12 | Link | Connection fault between main pcb and display pcb | CI |
| F13 | Link | PCB memory or sensing fault | Xtramax HE |
| F13 | Link | PCB memory or sensing fault | Ultrapower sxi |
| F13 | Link | PCB memory or sensing fault | Ultracom sxi |
| F13 | Link | PCB memory or sensing fault | Ultracom hxi |
| F13 | Link | PCB memory or sensing fault | Ultracom cx |
| F13 | Link | PCB memory or sensing fault | Ultracom cxi |
| F13 | Link | Main pcb connection fault | sxi |
| F13 | Link | Main pcb connection fault | SI |
| F13 | Link | Main pcb connection fault | hxi |
| F13 | Link | PCB memory or sensing fault | flexicom sx |
| F13 | Link | PCB memory or sensing fault | flexicom hx |
| F13 | Link | PCB memory or sensing fault | flexicom cx |
| F13 | Link | Main pcb connection fault | cxi |
| F13 | Link | Main pcb connection fault | CI Plus |
| F13 | Link | Main pcb connection fault | CI |
| F14 | Link | Gas valve control defective | Xtramax HE |
| F14 | Link | Gas valve control defective | Ultrapower sxi |
| F14 | Link | Gas valve control defective | Ultracom sxi |
| F14 | Link | Gas valve control defective | Ultracom hxi |
| F14 | Link | Gas valve control defective | Ultracom cx |
| F14 | Link | Gas valve control defective | Ultracom cxi |
| F14 | Link | Central heating flow temperature > 95 degrees | sxi |
| F14 | Link | Central heating flow temperature > 95 degrees | SI |
| F14 | Link | Central heating flow temperature > 95 degrees | hxi |
| F14 | Link | Gas valve control defective | flexicom sx |
| F14 | Link | Gas valve control defective | flexicom hx |
| F14 | Link | Gas valve control defective | flexicom cx |
| F14 | Link | Central heating flow temperature > 95 degrees | cxi |
| F14 | Link | Central heating flow temperature > 95 degrees | CI Plus |
| F14 | Link | Central heating flow temperature > 95 degrees | CI |
| F15 | Link | E-bus voltage failure | Ultrapower sxi |
| F15 | Link | E-bus voltage failure | Ultracom sxi |
| F15 | Link | E-bus voltage failure | Ultracom hxi |
| F15 | Link | E-bus voltage failure | Ultracom cx |
| F15 | Link | E-bus voltage failure | Ultracom cxi |
| F15 | Link | Gas valve stepper motor fault | sxi |
| F15 | Link | Gas valve stepper motor fault | SI |
| F15 | Link | E-bus voltage failure | flexicom sx |
| F15 | Link | E-bus voltage failure | flexicom hx |
| F15 | Link | E-bus voltage failure | flexicom cx |
| F15 | Link | Gas valve stepper motor fault | cxi |
| F15 | Link | Gas valve stepper motor fault | CI Plus |
| F15 | Link | Gas valve stepper motor fault | CI |
| F16 | Link | Flame detection fault | Xtramax HE |
| F16 | Link | Flame detection fault | sxi |
| F16 | Link | Flame detection fault | SI |
| F16 | Link | Flame detection fault | hxi |
| F16 | Link | Flame detection fault | cxi |
| F16 | Link | Flame detection fault | CI Plus |
| F16 | Link | Flame detection fault | CI |
| F17 | Link | Power supply is less than 170v | Xtramax HE |
| F17 | Link | Power supply is less than 170v | sxi |
| F17 | Link | Power supply is less than 170v | SI |
| F17 | Link | Power supply is less than 170v | hxi |
| F17 | Link | Power supply is less than 170v | cxi |
| F17 | Link | Power supply is less than 170v | CI Plus |
| F17 | Link | Power supply is less than 170v | CI |
| F18 | Link | User interface fault | Xtramax HE |
| F18 | Link | User interface fault | sxi |
| F18 | Link | User interface fault | SI |
| F18 | Link | User interface fault | hxi |
| F18 | Link | User interface fault | cxi |
| F18 | Link | User interface fault | CI Plus |
| F18 | Link | User interface fault | CI |
| F19 | Link | Central heating thermistor unplugged | Xtramax HE |
| F19 | Link | Central heating thermistor unplugged | sxi |
| F19 | Link | Central heating thermistor unplugged | SI |
| F19 | Link | Central heating thermistor unplugged | hxi |
| F19 | Link | Central heating thermistor unplugged | cxi |
| F19 | Link | Central heating thermistor unplugged | CI Plus |
| F19 | Link | Central heating thermistor unplugged | CI |
| F2 | Link | Fan | Xtramax HE |
| F2 | Link | Fan | sxi |
| F2 | Link | Fan/APS | SI |
| F2 | Link | Fan | hxi |
| F2 | Link | Fan | cxi |
| F2 | Link | Fan/APS | CI Plus |
| F2 | Link | Fan/APS | CI |
| F20 | Link | Software incompatibility | Xtramax HE |
| F20 | Link | Software incompatibility | sxi |
| F20 | Link | Software incompatibility | SI |
| F20 | Link | Software incompatibility | hxi |
| F20 | Link | Software incompatibility | cxi |
| F20 | Link | Software incompatibility | CI Plus |
| F20 | Link | Software incompatibility | CI |
| F22 | Link | Low water pressure or ignition temperature rise too slow | Ultrapower sxi |
| F22 | Link | Low water pressure or ignition temperature rise too slow | Ultracom sxi |
| F22 | Link | Low water pressure or ignition temperature rise too slow | Ultracom hxi |
| F22 | Link | Low water pressure or ignition temperature rise too slow | Ultracom cx |
| F22 | Link | Low water pressure or ignition temperature rise too slow | Ultracom cxi |
| F22 | Link | Low water pressure or ignition temperature rise too slow | flexicom sx |
| F22 | Link | Low water pressure or ignition temperature rise too slow | flexicom hx |
| F22 | Link | Low water pressure or ignition temperature rise too slow | flexicom cx |
| F23 | Link | Water circulation fault | Xtramax HE |
| F24 | Link | Cental heating return temperature > 90 degrees | Xtramax HE |
| F24 | Link | Cental heating return temperature > 90 degrees | sxi |
| F24 | Link | Cental heating return temperature > 90 degrees | hxi |
| F24 | Link | Central heating return temperature > 90 degrees | flexicom cx |
| F24 | Link | Central heating return temperature > 90 degrees | cxi |
| F25 | Link | Maximum temperature rise slope | Xtramax HE |
| F25 | Link | Circulation fault | Ultrapower sxi |
| F25 | Link | Circulation fault | Ultracom sxi |
| F25 | Link | Circulation fault | Ultracom hxi |
| F25 | Link | Circulation fault | Ultracom cx |
| F25 | Link | Circulation fault | Ultracom cxi |
| F25 | Link | Poor circulation | sxi |
| F25 | Link | Poor circulation | hxi |
| F25 | Link | Circulation fault | flexicom sx |
| F25 | Link | Circulation fault | flexicom hx |
| F25 | Link | Circulation fault | flexicom cx |
| F25 | Link | Poor circulation | cxi |
| F26 | Link | Maximum delta temperature | Xtramax HE |
| F26 | Link | Poor circulation | sxi |
| F26 | Link | Poor circulation | hxi |
| F26 | Link | Poor circulation | cxi |
| F3 | Link | Fan | Xtramax HE |
| F3 | Link | Fan unable to reach ignition speed | Ultrapower sxi |
| F3 | Link | Fan unable to reach ignition speed | Ultracom sxi |
| F3 | Link | Fan unable to reach ignition speed | Ultracom hxi |
| F3 | Link | Fan unable to reach ignition speed | Ultracom cx |
| F3 | Link | Fan unable to reach ignition speed | Ultracom cxi |
| F3 | Link | Fan unable to reach ignition speed | sxi |
| F3 | Link | Fan unable to reach ignition speed | hxi |
| F3 | Link | Fan unable to reach ignition speed | flexicom sx |
| F3 | Link | Fan unable to reach ignition speed | flexicom hx |
| F3 | Link | Fan unable to reach ignition speed | flexicom cx |
| F3 | Link | Fan unable to reach ignition speed | cxi |
| F3 | Link | Air fault | CI Plus |
| F4 | Link | Ignition fault | Xtramax HE |
| F4 | Link | Ignition fault | Ultrapower sxi |
| F4 | Link | Ignition fault | Ultracom sxi |
| F4 | Link | Ignition fault | Ultracom hxi |
| F4 | Link | Ignition fault | Ultracom cx |
| F4 | Link | Ignition fault | Ultracom cxi |
| F4 | Link | Ignition fault | sxi |
| F4 | Link | Ignition fault | SI |
| F4 | Link | Ignition fault | hxi |
| F4 | Link | Ignition fault | flexicom sx |
| F4 | Link | Ignition fault | flexicom hx |
| F4 | Link | Ignition fault | flexicom cx |
| F4 | Link | Ignition fault | cxi |
| F4 | Link | Ignition fault | CI Plus |
| F4 | Link | Ignition fault | CI |
| F43 | Link | Generic error | Ultrapower sxi |
| F43 | Link | Generic error | Ultracom sxi |
| F43 | Link | Generic error | Ultracom hxi |
| F43 | Link | Generic error | Ultracom cx |
| F43 | Link | Generic error | Ultracom cxi |
| F43 | Link | Generic error | flexicom sx |
| F43 | Link | Generic error | flexicom hx |
| F43 | Link | Generic error | flexicom cx |
| F5 | Link | Overheat Fault | Xtramax HE |
| F5 | Link | Overheat Fault | Ultrapower sxi |
| F5 | Link | Overheat Fault | Ultracom sxi |
| F5 | Link | Overheat Fault | Ultracom hxi |
| F5 | Link | Overheat Fault | Ultracom cx |
| F5 | Link | Overheat Fault | Ultracom cxi |
| F5 | Link | Overheat Fault | sxi |
| F5 | Link | Overheat Fault | SI |
| F5 | Link | Overheat Fault | hxi |
| F5 | Link | Overheat Fault | flexicom sx |
| F5 | Link | Overheat Fault | flexicom hx |
| F5 | Link | Overheat Fault | flexicom cx |
| F5 | Link | Overheat Fault | cxi |
| F5 | Link | Overheat Fault | CI Plus |
| F5 | Link | Overheat Fault | CI |
| F6 | Link | Central heating flow thermistor | Xtramax HE |
| F6 | Link | Central heating flow thermistor | Ultrapower sxi |
| F6 | Link | Central heating flow thermistor | Ultracom sxi |
| F6 | Link | Central heating flow thermistor | Ultracom hxi |
| F6 | Link | Central heating flow thermistor | Ultracom cx |
| F6 | Link | Central heating flow thermistor | Ultracom cxi |
| F6 | Link | Central heating flow thermistor | sxi |
| F6 | Link | Central heating flow thermistor | SI |
| F6 | Link | Central heating flow thermistor | hxi |
| F6 | Link | Central heating flow thermistor | flexicom sx |
| F6 | Link | Central heating flow thermistor | flexicom hx |
| F6 | Link | Central heating flow thermistor | flexicom cx |
| F6 | Link | Central heating flow thermistor | cxi |
| F6 | Link | Central heating flow thermistor | CI Plus |
| F6 | Link | Central heating flow thermistor | CI |
| F7 | Link | Domestic hot water thermistor | Xtramax HE |
| F7 | Link | Domestic hot water thermistor | sxi |
| F7 | Link | Domestic hot water thermistor | SI |
| F7 | Link | Domestic hot water thermistor | hxi |
| F7 | Link | Domestic hot water thermistor | flexicom sx |
| F7 | Link | Domestic hot water thermistor | flexicom cx |
| F7 | Link | Domestic hot water thermistor | cxi |
| F7 | Link | Domestic hot water thermistor | CI Plus |
| F7 | Link | Domestic hot water thermistor | CI |
| F70 | Link | Software incompatible | Ultrapower sxi |
| F70 | Link | Software incompatible | Ultracom sxi |
| F70 | Link | Software incompatible | Ultracom hxi |
| F70 | Link | Software incompatible | Ultracom cx |
| F70 | Link | Software incompatible | Ultracom cxi |
| F70 | Link | Software incompatible | flexicom sx |
| F70 | Link | Software incompatible | flexicom hx |
| F70 | Link | Software incompatible | flexicom cx |
| F73 | Link | Unable to see pump activate | Ultrapower sxi |
| F73 | Link | Unable to see pump activate | Ultracom sxi |
| F73 | Link | Unable to see pump activate | Ultracom hxi |
| F73 | Link | Unable to see pump activate | Ultracom cx |
| F73 | Link | Unable to see pump activate | Ultracom cxi |
| F73 | Link | Unable to see pump activate | flexicom sx |
| F73 | Link | Unable to see pump activate | flexicom hx |
| F73 | Link | Unable to see pump activate | flexicom cx |
| F77 | Link | Condensate pump error (optional) | Ultrapower sxi |
| F77 | Link | Condensate pump error (optional) | Ultracom sxi |
| F77 | Link | Condensate pump error (optional) | Ultracom hxi |
| F77 | Link | Condensate pump error (optional) | Ultracom cx |
| F77 | Link | Condensate pump error (optional) | Ultracom cxi |
| F77 | Link | Condensate pump error (optional) | flexicom sx |
| F77 | Link | Condensate pump error (optional) | flexicom hx |
| F77 | Link | Condensate pump error (optional) | flexicom cx |
| F8 | Link | Tank thermistor | Xtramax HE |
| F8 | Link | Tank thermistor (N/A For this appliance) | sxi |
| F8 | Link | Tank thermistor (N/A For this appliance) | SI |
| F8 | Link | Tank thermistor (N/A For this appliance) | hxi |
| F8 | Link | Tank thermistor (N/A For this appliance) | cxi |
| F8 | Link | Tank thermistor (N/A For this appliance) | CI Plus |
| F8 | Link | Tank thermistor (N/A For this appliance) | CI |
| F9 | Link | Water pressure sensor fault (please contact GW technical department for further information) | Xtramax HE |
| F9 | Link | Water pressure sensor fault, blocked flow filter or pump fault | Ultrapower sxi |
| F9 | Link | Water pressure sensor fault, blocked flow filter or pump fault | Ultracom sxi |
| F9 | Link | Water pressure sensor fault, blocked flow filter or pump fault | Ultracom hxi |
| F9 | Link | Water pressure sensor fault, blocked flow filter or pump fault | Ultracom cx |
| F9 | Link | Water pressure sensor fault, blocked flow filter or pump fault | Ultracom cxi |
| F9 | Link | Water pressure sensor fault (please contact GW technical department for further information) | sxi |
| F9 | Link | Water pressure sensor fault (please contact GW technical department for further information) | SI |
| F9 | Link | Earlier models only (please contact GW technical department for further information) | hxi |
| F9 | Link | Low water pressure Sensor | flexicom sx |
| F9 | Link | Low water pressure Sensor | flexicom hx |
| F9 | Link | Water pressure sensor fault, blocked flow filter or pump fault | flexicom cx |
| F9 | Link | Water pressure sensor fault (please contact GW technical department for further information | cxi |
| F9 | Link | Water pressure sensor fault (please contact GW technical department for further information | CI Plus |
| F9 | Link | Water pressure sensor fault (please contact GW technical department for further information | CI |
| No display or Er | Link | loose connection X51 | Ultrapower sxi |
| No display or Er | Link | loose connection X51 | Ultracom sxi |
| No display or Er | Link | loose connection X51 | Ultracom hxi |
| No display or Er | Link | loose connection X51 | Ultracom cx |
| No display or Er | Link | loose connection X51 | Ultracom cxi |