Vokera Boiler Issues: Errors and Fault Codes

Your Vokera boiler may occasionally display a fault code to tell you that it has developed a fault. The boiler will automatically display the unique fault code, which can then be used to determine why the boiler isn’t operating properly. When a fault code appears, the appropriate code is shown flashing on the display and is sometimes accompanied by a symbol. If your Vokera boiler is showing a fault code, we recommend you contact a Gas Safe registered engineer who will be able to safely find the fault and carry out any fixes and repairs that are needed.

As it’s always useful to know what each fault code means, we’ve put together a table that explains the cause of each Vokera boiler fault code.

Vokera Boiler Fault Codes         

FAULT CODE SYMBOL CAUSE/ACTION
01 N/A Burner has failed to ignite or flame supervision system has failed to detect a flame. Check there’s an incoming gas supply. If you have gas, contact an engineer to fix a problem with the spark electrode, polarity, integrity of flue system, gas valve or ignition control PCB.
02 N/A Boiler has overheated. Call an engineer to check the thermostat, thermistor, pump and gas pressure.
03 N/A Boiler flue has developed a fault. Call an engineer to check fan operation, flue venture, air pressure switch and flue system.
04 N/A Low boiler pressure. Check water pressure and pressure gauge. If problem persists, contact an engineer.
05, 06 or 09 N/A PCB fault. Call an engineer.
07 N/A Thermistor has developed a fault. Call an engineer.
08 N/A The burner thermostat has been activated. Call an engineer.
10 Spanner or RESET or both No flame detected.
11 Spanner or RESET or both False flame.
12 Spanner or RESET or both Restart ignition.
13 or 14 Spanner or RESET or both Call an engineer to check wiring harness.
15 Spanner or RESET or both False flame.
20 Spanner or RESET or both High limit thermostat/fume thermostat.
21, 22, 23 or 29 Spanner or RESET or both Call an engineer to check the wiring harness.
24, 25, 26 or 27 Spanner or RESET or both High limit flow temperature probe.
28 Spanner or RESET or both Flow/return error.
34 Spanner or RESET or both Fan error (start-up).
37 Spanner or RESET or both Fan error (high rpm).
40 or 41 Spanner or RESET or both Low water pressure.
42 Spanner or RESET or both Pressure transducer fault.
50 – 59 Spanner or RESET or both Internal PCB failure.
60 Spanner or RESET or both Domestic hot water (DHW) NTC error.
70 or 71 Spanner or RESET or both Flow NTC error (2nd CH).
72 Spanner or RESET or both Return NTC error (2nd CH).
77 Spanner or RESET or both Over heat underfloor thermostat (2nd CH).
78 or 79 Spanner or RESET or both Flow/return error (2nd CH).
80 – 83 Spanner or RESET or both Internal fault.
91 Spanner or RESET or both Condensing heat exchanger cleaning requirement.
_St N/A AUTOSTOP. Call an engineer.
_CL N/A Call an engineer for service.
A01 Flame and bell Ignition failure, flame not sensed or internal fault. Reset, ensure gas supply is turned on. If problem persists, call an engineer.
A01 No symbol No flame
A02 Bell Limit thermostat fault. Reset, ensure sufficient water pressure. If problem persists, call an engineer.
A02 No symbol The burner has shut off three times while a request was in progress. Defective ignition transformer, defective ignition transformer power cable or flue gas pipe obstructed. Call an engineer.
A03 Bell Fan tacho signal fault. Reset. If problem persists, call an engineer.
A03 No symbol The delivery temperature has exceeded the set value.
A04 Water and bell Insufficient system water pressure. Check and refill system pressure, then reset appliance. If problem persists, call an engineer.
A04 No symbol Possible safety thermostat intervention due to overheating.
A05 No symbol Temporary internal fault.
A06 Bell DHW thermistor fault. Reset. If problem persists, call an engineer.
A07 Bell Primary (flow) thermistor fault, primary (flow) thermistor over temperature, temperature differential. Reset the appliance. If problem persists, call an engineer.
A07 No symbol Low temperature zone safety thermostat intervention.
A08 Bell Primary (return) thermistor fault, return thermistor over temperature, temperature differential inverted. Reset. If problem persists, call an engineer.
A09 Bell Flue thermistor over temperature or flue thermistor counter fault. Reset. If problem persists, call an engineer.
A11 Bell False flame. Temporary fault.
A77 Bell Low temperature thermostat fault. Reset. If problem persists, call an engineer.
Adj N/A Calibration. No action required.
ACO Bell Service operation. No action required.
N/A Flame Flame on. No action required.
Hours N/A Stand-by. No action required.
P N/A Preheating function active. No action required.
P blinking N/A Preheating function running. No action required.
AL10 N/A Ignition failure/no flame sensed, condense sensor activated. Reset. If problem persists, call an engineer.
AL20 N/A Limit thermostat fault. Reset. If problem persists, call an engineer.
AL21 N/A External device fault. Reset. If problem persists, call an engineer.
AL26 N/A Return temperature too high. Reset. If problem persists, call an engineer.
AL28 N/A Temperature differential inverted (return sensor temperature higher than flow sensor temperature). Reset. If problem persists, call an engineer.
AL34 N/A Fan tacho signal fault. Reset. If problem persists, call an engineer.
AL40 or AL41 N/A Insufficient system water pressure. Check/refill system and reset. If problem persists, call an engineer.
AL52 N/A Internal fault. Call an engineer.
AL55 or AL60 N/A Jumper tag fault. Call an engineer.
AL71 N/A Primary (flow) thermistor fault. Call an engineer.
AL73 N/A Return thermistor fault. Call an engineer.
AL74 N/A Variation on temperature of primary and/or return too high. Call an engineer.
AL79 N/A Flow temperature too high or temperature differential between primary and return too high. Call an engineer.
E01 N/A Delivery temperature probe open.
E02 N/A Return temperature probe open.
E08 N/A Domestic hot water temperature probe open.
E11 N/A Delivery temperature probe short-circuit.
E12 N/A Return temperature probe short-circuit.
E18 N/A Domestic hot water temperature probe short-circuit.
E21 N/A Phase and neutral connections inverted.
E35 N/A Flue gas probe short-circuit or flue gas temperature too high.
E36 N/A Flue gas probe open.
E37 N/A Differential pressure switch intervention or water pressure too low.
U10 N/A Low temperature system delivery temperature probe interrupted.
U11 N/A Low temperature system delivery temperature probe short-circuit.
U21 N/A Delivery temperature higher than 55 (could be due to a mixer valve fault).
U99 N/A Electrical power supply interruption on the multi-temperature kits’ electronic board.