Vokera Mynute 23E Fault codes & diagnostics

30 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.

Combi Natural Gas 23 kW Discontinued

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1 Emergency 28 High 1 Low
Just want the most common Vokera Mynute 23E faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 30 documented codes

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10

Your boiler has failed to ignite and cannot produce heat, which could be due to a gas supply issue, a blocked exhaust pipe, or an electrical wiring error.

High DIY-safe £100-£250

What to check first

  1. Check if other gas appliances, like a hob, are working to confirm your gas supply is active.
  2. Ensure your gas meter has credit and the handle is in the 'on' position.
  3. Visually check the outside flue pipe for any obvious obstructions like bird nests or debris.
  4. Try resetting the boiler by turning the control knob to the 'Reset' position let it sit for a few seconds.

Parts commonly replaced

  • Ignition Electrode
  • Gas Valve
  • Printed Circuit Board (PCB)

Related codes

Full explanation for 10
AF

Your boiler has detected very cold temperatures and has automatically turned itself on to prevent the internal pipes from freezing.

Low DIY-safe

What to check first

  1. Check that your gas and electricity supplies are still active
  2. Ensure any exposed external pipework (condensate pipe) is insulated or not frozen
  3. Monitor the boiler; the code should disappear once the water temperature inside the unit rises sufficiently
Full explanation for AF
AL10

Your boiler has failed to light, which is often caused by a blocked condensation pipe or an issue with the ignition system.

High DIY-safe £100-280

What to check first

  1. Check if your gas supply is turned on and other gas appliances are working.
  2. If it is freezing outside, check if the plastic condensation pipe leading outdoors is frozen and thaw it with warm water.
  3. Press the Reset button on the control panel to see if the boiler restarts.

Parts commonly replaced

  • Ignition Electrode
  • Gas Valve
  • Condensate Trap Cleaned/Replaced
Full explanation for AL10
AL20

Your boiler has shut down because it has detected a temperature that is too high, often caused by a blockage or a pump failure.

High DIY-safe £100-280

What to check first

  1. Check that all radiator valves are fully open
  2. Ensure the system water pressure is between 1 and 1.5 bar
  3. Turn the selector switch to 'OFF/RESET' for a few seconds and then back to 'ON'

Parts commonly replaced

  • Overheat Thermostat
  • Circulation Pump
  • Main Heat Exchanger

Related codes

Full explanation for AL20
AL21

Your boiler has shut down because a safety device or an external controller has detected an issue and stopped the system from running.

High Engineer only £90-180

Parts commonly replaced

  • Limit thermostat
  • External control wiring
  • Main PCB

Related codes

Full explanation for AL21
AL26

Your boiler has sensed that the water returning to it is too hot, which suggests that the heat is not being effectively pumped away through your radiators.

High DIY-safe £120-280

What to check first

  1. Check that all radiator valves are fully open
  2. Ensure the central heating bypass valve is not closed
  3. Turn the boiler off and on again to see if the pump restarts

Parts commonly replaced

  • Circulation Pump
  • Return NTC Thermistor
  • Internal Filter

Related codes

Full explanation for AL26
AL28

Your boiler has detected that the water coming back from your radiators is hotter than the water going out, which usually means the water isn't circulating correctly or a sensor is faulty.

High Engineer only £90-180

Parts commonly replaced

  • Flow NTC sensor
  • Return NTC sensor
  • Circulation pump

Related codes

Full explanation for AL28
AL34

Your boiler has stopped working because it cannot correctly detect if the internal fan is spinning at the right speed to safely clear away exhaust fumes.

High Engineer only £180-350

Parts commonly replaced

  • Fan motor
  • Fan tacho sensor
  • Printed Circuit Board (PCB)
Full explanation for AL34
AL40

Your boiler has stopped working because the water pressure in the central heating system has dropped too low.

High DIY-safe £0-120

What to check first

  1. Locate the external filling loop, which is usually a flexible silver hose with one or two small valves.
  2. Slowly open the valve(s) to allow water into the system while watching the pressure gauge.
  3. Close the valves tightly once the needle on the gauge reaches between 1.0 and 1.5 bar.

Parts commonly replaced

  • Filling loop
  • Expansion vessel
  • Pressure relief valve

Related codes

Full explanation for AL40
AL41

Your boiler has stopped working because the water pressure in the central heating system has dropped too low.

High DIY-safe £0-120

What to check first

  1. Locate the external filling loop, which is usually a flexible silver hose with one or two small valves.
  2. Open the valve(s) slowly to allow water into the system while watching the pressure gauge.
  3. Close the valves tightly once the gauge reaches between 1.0 and 1.5 bar, then restart the boiler.

Parts commonly replaced

  • Filling loop
  • Expansion vessel re-pressurisation
  • Pressure sensor

Related codes

Full explanation for AL41
Showing 11–20 of 30
AL52

Your boiler has stopped working because of an internal communication error with its main brain, often caused by a failing circuit board.

High Engineer only £250-400

Parts commonly replaced

  • Main PCB (Printed Circuit Board)
  • Wiring Harness

Related codes

Full explanation for AL52
AL55

Your boiler's electronic control board has been set up with incorrect configuration settings or a missing physical connection, preventing it from operating.

High Engineer only £100-280

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Jumper Tags

Related codes

Full explanation for AL55
AL60

Your boiler’s internal computer has lost its configuration settings and no longer knows how to run safely.

High Engineer only £120-350

Parts commonly replaced

  • Main Circuit Board (PCB)
  • Jumper Tags

Related codes

Full explanation for AL60
AL71

Your boiler has detected an issue with the sensor that monitors the temperature of the water leaving the unit, preventing it from heating up properly.

High Engineer only £90-160

Parts commonly replaced

  • NTC Flow Thermistor
  • Thermistor Wiring Harness

Related codes

Full explanation for AL71
AL73

Your boiler has detected a problem with the sensor that monitors the temperature of the water returning from your heating system, causing it to stop running for safety.

High Engineer only £90-160

Parts commonly replaced

  • Return NTC thermistor
  • Wiring harness / Connector

Related codes

Full explanation for AL73
AL74

Your boiler has detected that the water temperature is changing too quickly or unevenly, usually because the water isn't flowing through the system properly.

High DIY-safe £120-280

What to check first

  1. Check that your boiler pressure is between 1.0 and 1.5 bar on the pressure gauge
  2. Ensure all radiator valves are fully open to allow water to circulate
  3. Bleed your radiators to remove any trapped air pockets

Parts commonly replaced

  • Circulation Pump
  • NTC Temperature Sensors
  • Main Heat Exchanger (Descaling)

Related codes

Full explanation for AL74
AL79

Your boiler has shut down because the internal water has become too hot or isn't circulating through the system quickly enough.

High DIY-safe £120-£350

What to check first

  1. Ensure all radiator valves (TRVs) are turned to the maximum setting
  2. Check that the central heating valves underneath the boiler are fully open
  3. Check the system pressure gauge and top up to 1.5 bar if it is low
  4. Turn the boiler off and back on to attempt a reset

Parts commonly replaced

  • Circulation pump
  • NTC Temperature Sensor
  • Main Heat Exchanger (Descaling)

Related codes

Full explanation for AL79
Appliance fires then lockouts

Your boiler is struggling to stay lit because it either isn't receiving enough fuel or cannot safely vent its exhaust gases.

Emergency Engineer only £120-250

Parts commonly replaced

  • Gas valve
  • Flue seals
  • PCB
Full explanation for Appliance fires then lockouts
Appliance stays fired

Your boiler is continuing to burn gas and run even though your heating controls have told it to stop, which is likely caused by a stuck control valve or a wiring issue.

High Engineer only £140-280

Parts commonly replaced

  • 2-Port Motorised Valve
  • 3-Port Mid-position Valve
  • External Programmer
Full explanation for Appliance stays fired
Appliance wont fire

Your boiler is failing to start because it cannot detect a demand for heat, the water pressure is too low, or an internal electrical fuse has failed.

High DIY-safe £90-180

What to check first

  1. Check your pressure gauge; if it is below 1 bar, use the filling loop to top it up to 1.5 bar
  2. Switch the boiler off at the fused spur, check the 3A fuse in the plug or spur, and replace if it has blown
  3. Turn off your room thermostat and timer to see if the boiler resets; if it fires, the issue lies with your external controls

Parts commonly replaced

  • 3A Fuse
  • Filling loop
  • Pressure gauge
  • PCB
Full explanation for Appliance wont fire
Showing 21–30 of 30
LD1

Your boiler has detected a safety fault and has locked itself out to prevent damage or unsafe operation.

High Engineer only £100-350

Parts commonly replaced

  • Overheat Thermostat
  • Ignition Electrode
  • Printed Circuit Board (PCB)
  • Gas Valve

Related codes

Full explanation for LD1
Low-pressure fault code

Your boiler has stopped working because the water pressure inside the system has dropped too low to allow it to run safely.

High DIY-safe £0-120

What to check first

  1. Locate the filling loop (a flexible silver hose) underneath or near the boiler.
  2. Slowly open the one or two taps on the loop until you hear water entering the system.
  3. Watch the pressure gauge until it reaches between 1.0 and 1.5 bar, then close the taps fully.

Parts commonly replaced

  • Filling loop valve
  • Expansion vessel
  • Pressure sensor
Full explanation for Low-pressure fault code
Pressure below 0.5 bar

Your boiler has stopped working because the water pressure is too low to operate safely.

High DIY-safe £0-120

What to check first

  1. Locate the filling loop (a flexible silver hose) underneath or near the boiler.
  2. Slowly open the one or two taps/valves on the hose until you hear water entering.
  3. Close the taps once the pressure gauge on the front of the boiler reaches between 1.0 and 1.5 bar.

Parts commonly replaced

  • Filling loop valve
  • Pressure sensor
  • Expansion vessel
Full explanation for Pressure below 0.5 bar
Pressure fall below 0.5 BAR

Your boiler has detected that the water pressure is too low to operate safely and has switched itself off to prevent damage.

High DIY-safe £0-120

What to check first

  1. Locate the external filling loop (the flexible silver hose) under or near the boiler.
  2. Slowly open the one or two taps on the hose until you hear water entering.
  3. Watch the pressure gauge and close the taps once the needle reaches between 1 and 1.5 bar.

Parts commonly replaced

  • Filling loop valve
  • Pressure sensor
  • Expansion vessel
Full explanation for Pressure fall below 0.5 BAR
PressureGauge < 0.5 BAR

Your boiler has stopped working because the water level inside the system has dropped too low to operate safely.

High DIY-safe £0-120

What to check first

  1. Locate the filling loop, which is usually a flexible silver hose with one or two small valves underneath the boiler.
  2. Slowly open the valve(s) to allow cold water into the system, watching the pressure gauge rise.
  3. Close the valves tightly once the pressure gauge reaches between 1.0 and 1.5 BAR.

Parts commonly replaced

  • Filling loop hose
  • Expansion vessel
  • Pressure relief valve
Full explanation for PressureGauge < 0.5 BAR
Reset Light (Ignition)

Your boiler is unable to light the gas to start the heating process, causing the system to lock out for safety.

High DIY-safe £100-280

What to check first

  1. Check if your gas supply is active by testing another gas appliance like a hob.
  2. Ensure the gas stopcock valve is fully open.
  3. Press and hold the reset button for a few seconds to attempt a restart.

Parts commonly replaced

  • Ignition Electrode
  • Gas Valve
  • Spark Lead
  • Printed Circuit Board (PCB)
Full explanation for Reset Light (Ignition)
Reset Light (Overheat)

Your boiler has switched itself off as a safety precaution because it has either failed to light or has become too hot.

High DIY-safe £90-250

What to check first

  1. Locate the mode selector switch on the front control panel.
  2. Turn the switch to the 'RESET' position and hold it for a few seconds.
  3. Turn the switch back to the original 'Heating' or 'Hot Water' position and wait for the boiler to restart.

Parts commonly replaced

  • Overheat Thermostat
  • Circulation Pump
  • Ignition Electrode
Full explanation for Reset Light (Overheat)
Reset light illuminated

Your boiler has stopped working because it couldn't start properly or became too hot, so it has safely turned itself off to prevent any damage.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • PCB
  • Overheat thermostat
Full explanation for Reset light illuminated
Reset light is on

Your boiler has switched itself off as a safety precaution because it either failed to light properly or got too hot.

High DIY-safe £90-280

What to check first

  1. Locate the mode selector switch on the front control panel.
  2. Turn the switch to the 'RESET' position and hold it for a few seconds.
  3. Return the switch to the 'ON' position and wait for the boiler to attempt to restart.

Parts commonly replaced

  • Ignition Electrode
  • Gas Valve
  • Overheat Thermostat
  • Printed Circuit Board (PCB)
Full explanation for Reset light is on
Reset light on

Your boiler has safety-locked itself to stop the flow of gas, likely because it failed to light or lost its flame.

High DIY-safe £100-300

What to check first

  1. Locate the mode selector switch on the front panel.
  2. Turn the switch to the 'RESET' position and hold it for a few seconds.
  3. Return the switch to your desired mode (heating or hot water) and wait for the boiler to restart.

Parts commonly replaced

  • Ignition Electrode
  • Gas Valve
  • PCB

Related codes

Full explanation for Reset light on