| Fault Codes | Fault Description | Possible Causes |
|---|---|---|
| Fault Code F1 | Ignition Failure | Insufficient Inlet Working Gas Pressure At The Appliance |
| Flue Problem | ||
| Spark Generation Issue | ||
| Incorrect Gas Valve Adjustment (Minimum Burner Pressure Set Too Low) | ||
| Flame Rectification Issue | ||
| Combustion Issue (Poor Flame Picture) | ||
| Software Error On The Main PCB Or The User Interface PCB | ||
| Fault Code F2 | Air Fault | Fan Fault |
| Fan Venturi Blocked | ||
| PCB Fault (No Power To The Fan) | ||
| Wiring Harness Fault Between The Fan And The Main PCB | ||
| The Air Pressure Switch Is Not Switching To The N/O Position When The Fan Is Running | ||
| The Air Pressure Switch Jammed In The “Made” Position Prior To The Fan Operation | ||
| Fault Code F3 | Air Fault | Fan Fault |
| Fan Venturi Blocked | ||
| PCB Fault (No Power To The Fan) | ||
| Wiring Harness Fault Between The Fan And The Main PCB | ||
| The Air Pressure Switch Is Not Switching To The N/O Position When The Fan Is Running | ||
| The Air Pressure Switch Jammed In The “Made” Position Prior To The Fan Operation | ||
| Fault Code F4 | Flame Sensing Fault | Insufficient Inlet Working Gas Pressure At The Appliance |
| Flue Problem | ||
| Incorrect Gas Valve Adjustment (Minimum Burner Pressure Set Too Low) | ||
| Poor Combustion (Poor Flame Picture) | ||
| Flame Sensing Electrode Faulty Or Incorrectly Positioned | ||
| Incoming Power Supply Issue (Reverse Polarity, Neutral Fault, Earth Fault) | ||
| Software Error On The Main PCB Or The User Interface PCB | ||
| Fault Code F5 | Overheat Fault | The Overheat Thermostat Has Activated In The Appliance Due To Poor Circulation (115C) |
| Pump Not Running | ||
| Appliance Heating Return Filter Blocked | ||
| Air Lock Within The Boiler Or The System | ||
| Blockage Within The Boiler Or The System | ||
| System Design Issue | ||
| Insufficient System Bypass | ||
| NTC Thermistor Out Of Calibration (Should Read 12Kohms @ 20C) | ||
| Harness Fault Between The Overheat Thermostat And The Main PCB | ||
| Fault Code F6 | Thermistor Fault | The NTC Thermistor Has Gone Open Circuit (Should Read 12Kohms @ 20C) |
| Wiring Harness Fault Or Connection Fault Between Thermistor And The Main PCB |
Vaillant CI-SI Boiler Error Codes
Vaillant CI-SI Boiler Error Codes