Vaillant CI-SI Boiler Error Codes

Vaillant CI-SI Boiler Error Codes

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

Got the right tools for your trade?