Vokera Boiler Fault Codes and Errors

Vokera is a budget boiler brand that offers a range of Combi and system boilers with different kW options suitable for various homes. However, their low budget nature makes them prone to faults and unreliable compared to other leading brands like the Worcester Bosch.
Fortunately, their design enables them to display error codes, which are alphanumeric codes that underline the faults with the Vokera boiler. These error codes allow you or the qualified heating engineer to deduce the problem and how best to tackle the issue.
As such, if you notice error codes displayed by your boiler, first try resetting it. And if it doesn’t work, call a certified heating engineer.
What do red and green lights signify in a Vokera boiler?
If your boiler flashes red or is constantly on red, it spells trouble. Your boiler flashing a red light implies that it has a fault that requires urgent attention. And as the fault can be due to many reasons, you should get a qualified engineer to check your boiler out. On the other hand, a constant red means your boiler has gone into lockout, a safety procedure initiated to avoid further damage.
A lockout could be initiated for several reasons. Among these reasons are the boiler overheating, the pump not circulating hot water into the central heating system, and a fan defect resulting in leaking harmful gases.
On the other hand, if you notice red and green lights at the same time from the Vokera boiler, it might have the following problems:
- The boiler is in service mode after a recent boiler service.
- Incorrect water pressure.
- The heating temperature sensors are faulty.
A constant green light on your Vokera boiler is a good sign. It means the boiler is running optimally with no faults. However, when the green light flashes, it implicates an issue. For instance, a flashing green light implies that the boiler has a faulty hot water sensor or is on standby.
How to reset a Vokera boiler?
Sometimes when a boiler displays error codes, all it needs is a simple reset. Resetting the boiler can clear the error and enable it to resume normal functioning. To reset a Vokera boiler, change the mode selector to ‘off’ or ‘reset’ and then move it back to ‘Heating and hot water’ or ‘Hot water only’.
The above procedure should restart the boiler to start working. If the boiler fails to restart, call a qualified gas engineer.
Vokera boiler fault codes for various models
FAULT CODE | SYMBOL | CAUSE | Action |
01 | N/A | The burner does not ignite/ the flame supervision system does not detect a flame. | Ensure there is a gas supply. If so, then contact a qualified engineer. The problem might be with the spark electrode, polarity, integrity of flue system, gas valve or ignition control PCB. |
02 | N/A | The boiler is overheating. | Call a qualified engineer. The problem might be with the thermostat, thermistor, pump or gas pressure. |
03 | N/A | Boiler flue has a fault. | Call a qualified engineer. The problem might be the fan operation, flue venture, air pressure switch or flue system. |
04 | N/A | The boiler has low pressure | Repressurise the boiler system. If the problem persists, contact a qualified engineer. |
05, 06 or 09 | N/A | Public Circuit Board (PCB) fault | Call a qualified engineer. |
07 | N/A | Thermistor has a fault. | Call a qualified engineer. |
08 | N/A | The burner thermostat is active | Call a qualified engineer. |
10 | Spanner or RESET or both | No visible flame. | |
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 a qualified engineer to check the wiring harness. | |
15 | Spanner or RESET or both | False flame. | |
20 | Spanner or RESET or both | A high limit thermostat or fume thermostat. | |
21, 22, 23 or 29 | Spanner or RESET or both | Call a qualified engineer to check the wiring harness. | |
24, 25, 26 or 27 | Spanner or RESET or both | A high limit flow temperature probe. | |
28 | Spanner or RESET or both | Central heating flow or return error. | |
34 | Spanner or RESET or both | Fan error while starting up. | |
37 | Spanner or RESET or both | Fan error (high revolutions per minute). | |
40 or 41 | Spanner or RESET or both | Low water pressure in the boiler system | Repressurise your boiler |
42 | Spanner or RESET or both | There is a pressure transducer fault. | |
50 – 59 | Spanner or RESET or both | Internal Public Circuit Board failure. | Call a qualified heating engineer |
60 | Spanner or RESET or both | Domestic hot water (DHW) or NTC error. | |
70 or 71 | Spanner or RESET or both | Flow Negative Thermistor Coefficient error (2nd CH). | |
72 | Spanner or RESET or both | Return Negative Thermistor Coefficient error (2nd CH). | |
77 | Spanner or RESET or both | The underfloor thermostat is overheating (2nd CH). | |
78 or 79 | Spanner or RESET or both | Central heating flow or return error (2nd CH). | |
80 – 83 | Spanner or RESET or both | There is an internal fault. | |
91 | Spanner or RESET or both | Required to clean the condensing heat exchanger. | |
_St | N/A | AUTOSTOP. | Call a qualified engineer. |
_CL | N/A | Call a qualified engineer for service. | |
A01 | Flame and bell | There is an ignition failure, sense of no flame or an internal fault. | Reset and ensure gas supply is on. If the problem persists, call a qualified engineer. |
A01 | No symbol | No flame | |
A02 | Bell | There is a limit thermostat fault. | Reset and ensure sufficient water pressure. If the problem persists, call a qualified engineer. |
A02 | No symbol | The burner shuts off severally (thrice) while a request was in progress: defective ignition transformer, transformer power cable, or a flue gas pipe obstruction. | Call a qualified engineer. |
A03 | Bell | A fan tacho signal fault. | Reset. If the problem persists, call a qualified engineer. |
A03 | No symbol | The delivery temperature has exceeded the set value. | |
A04 | Water and bell | Insufficient water pressure in the system. | Repressurise, then reset the appliance. If the problem persists, call a qualified engineer. |
A04 | No symbol | A possible safety thermostat intervention, caused by overheating | |
A05 | No symbol | A temporary internal fault. | |
A06 | Bell | A DHW thermistor fault. | Reset. If the problem persists, call a qualified engineer. |
A07 | Bell | Temperature differential or a fault with the primary thermistor (flow) | Reset the appliance. If the problem persists, call a qualified engineer. |
A07 | No symbol | Low-temperature zone. The intervention of a safety thermistor | |
08 | Bell | Primary (return) thermistor fault, return thermistor over set temperature or temperature differential inverted. | Reset. If the problem persists, call a qualified engineer. |
A09 | Bell | Flue thermistor temperature is higher than set temperature or flue thermistor counter fault. | Reset. If the problem persists, call a qualified engineer. |
A11 | Bell | False flame or a temporary fault. | |
A77 | Bell | Low-temperature thermostat fault. | Reset. If the problem persists, call a qualified engineer. |
Adj | N/A | Calibration. | It requires no action. |
ACO | Bell | Service operation. | It requires no action. |
N/A | Flame | The flame is on. | It requires no action. |
Hours | N/A | Stand-by. | It requires no action. |
P | N/A | Preheating function is active. | It requires no action. |
P blinking | N/A | Preheating function is running. | It requires no action. |
AL10 | N/A | Ignition failure or sense of no flame, condense sensor is active. | Reset. If the problem persists, call a qualified engineer. |
AL20 | N/A | Limit thermostat fault. | Reset. If the problem persists, call a qualified engineer. |
AL21 | N/A | External device fault. | Reset. If the problem persists, call a qualified engineer. |
AL26 | N/A | The return temperature is too high. | Reset. If the problem persists, call a qualified engineer. |
AL28 | N/A | The temperature differential is inverted. | Reset. If the problem persists, call a qualified engineer. |
AL34 | N/A | A fan tacho signal fault. | Reset. If the problem persists, call a qualified engineer. |
AL40 or AL41 | N/A | Insufficient water pressure in the system. | Check/refill system and reset. If the problem persists, call a qualified engineer. |
AL52 | N/A | There is an internal fault. | Call a qualified engineer. |
AL55 or AL60 | N/A | A jumper tag fault. | Call a qualified engineer. |
AL71 | N/A | Fault in the primary flow thermistor. | Call a qualified engineer. |
AL73 | N/A | Fault in the primary return thermistor. | Call a qualified engineer. |
AL74 | N/A | A variation on the temperature of primary return or return is too high. | Call a qualified engineer. |
AL79 | N/A | The flow temperature is too high, or the temperature differential between primary and return is too high. | Call a qualified engineer. |
E01 | N/A | The delivery temperature probe is open. | |
E02 | N/A | The return temperature probe is open. | |
E08 | N/A | DHW temperature probe is open. | |
E11 | N/A | The delivery temperature probe has a short circuit. | |
E12 | N/A | The return temperature probe has a short circuit. | |
E18 | N/A | DHW temperature probe has a short circuit. | |
E21 | N/A | Phase and neutral connections inverted. | |
E35 | N/A | The flue gas probe has a short circuit, or temperatures in the gas flue are too high. | |
E36 | N/A | The flue gas probe is open. | |
E37 | N/A | Differential pressure switch intervention or water pressure is 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 | The delivery temperature is higher than 55, which could be due to a mixer valve fault). | |
U99 | N/A | There is an electrical power supply interruption on the multi-temperature kits’ electronic board. |
You will need to contact a qualified gas engineer if you notice the faults below with your Vokera boiler:
- Whistling or Banging noises – It could relate to an ignition problem or a leak
- No hot water or heating – This is due to faulty diverter valves and may produce flashing lights on the system.
- Low pressure – If your boiler does not operate properly after repressurising, there might be a leak or a problem with the valves.
- Leaks – They can happen anywhere in the system and are not always visible. They need immediate attention.
- Boiler shutting down – A faulty pump or thermostat could cause this.
- Problems with thermostat – It is usually a low-temperature fault that requires replacement.
- Frozen condensate pipes – Needs warm water to be poured over the external pipes.
- No pilot light – The thermocouple may need a replacement.
- Cold radiators – May indicate too much sludge accumulation in the system.