Vokera Compact HE Fault codes & diagnostics

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

Combi Natural GasLPG 24-29 kW 2005-2012 Discontinued

Replaced by: Compact A

Download the Vokera Compact HE manual The official installation & service manual (PDF) — the exact document these fault codes were verified against. PDF

This boiler uses LED flash patterns

Count the flashes in one repeating group before the pause. That number is your fault code. Do not reset until you have noted it. How to read fault codes →

Severity at a glance

Each cell = one fault code. Hover to identify.
21 High 5 Medium
Just want the most common Vokera Compact HE faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 26 documented codes

Tap any card for details

LED / flash-pattern codes
RED LED BLINKS

Your boiler has likely overheated or has an issue with its internal fan system, causing it to shut down for safety.

High DIY-safe £120-280

What to check first

  1. Turn the mode selector switch to 'OFF/RESET' for a few seconds.
  2. Move the switch back to either 'Hot Water' or 'Heating and Hot Water' mode.
  3. Check that all radiator valves are open and your wireless thermostat has working batteries.

Parts commonly replaced

  • High Limit Thermostat
  • Air Pressure Switch
  • Fan Assembly

Related codes

Full explanation for RED LED BLINKS
Digital codes
APS fault

Your boiler is struggling to clear exhaust gases properly, which has triggered a safety pause to prevent it from operating until the airflow is corrected.

High Engineer only £120-250

Parts commonly replaced

  • Air Pressure Switch
  • Venturi
  • Flue assembly
Full explanation for APS fault
condense pressure switch

Your boiler has detected that water is failing to drain away properly from the internal system, so it has safely shut down to prevent internal flooding or damage.

High Engineer only £120-220

Parts commonly replaced

  • Condensate trap
  • Condensate pressure switch
  • Condensate pipework
Full explanation for condense pressure switch
DHW NTC fault

Your boiler is struggling to accurately detect the temperature of the water being heated for your taps, which means it may fail to provide hot water or heat it to the wrong temperature.

Medium Engineer only £120-200

Parts commonly replaced

  • Domestic Hot Water (DHW) NTC Thermistor
Full explanation for DHW NTC fault
DHW thermistor fault

Your boiler is struggling to accurately measure the temperature of the water being heated for your taps, which prevents it from providing consistent hot water.

Medium Engineer only £120-180

Parts commonly replaced

  • DHW NTC thermistor sensor
  • Wiring harness
Full explanation for DHW thermistor fault
fan/flue problem

Your boiler has detected an issue with the system that removes waste gases, meaning it has safely shut down to prevent the release of fumes into your home.

High Engineer only £150-300

Parts commonly replaced

  • Flue fan
  • Air pressure switch
  • Venturi tube
  • PCB
Full explanation for fan/flue problem
Fault light is on

Your boiler has detected a general internal error and has locked itself out for safety, meaning your heating and hot water will not work until it is reset or repaired.

High DIY-safe £100-350

What to check first

  1. Check if your gas prepay meter has credit
  2. Rotate the mode selector switch to the 'OFF/RESET' position, wait five seconds, then move it back to 'Auto' or 'Hot Water Only'
  3. Check your pressure gauge is between 1 and 1.5 bar; if it is too low, top it up using the filling loop

Parts commonly replaced

  • Ignition Electrode
  • Printed Circuit Board (PCB)
  • Thermistor (NTC Sensor)
Full explanation for Fault light is on
Green LED Off, Red LED Off

Your boiler has no power and is completely unresponsive, meaning the heating and hot water will not work.

High DIY-safe £100-350

What to check first

  1. Check if your home's main fuse box has tripped a circuit.
  2. Ensure the boiler's isolation switch (usually a white switch near the unit) is turned on.
  3. Check if other appliances in the house have power to rule out a local power cut.

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Internal Fuse
  • External 3A Fuse

Related codes

Full explanation for Green LED Off, Red LED Off
Green LED Off, Red LED On

Your boiler has experienced a safety lockout and has shut itself down to prevent damage.

High DIY-safe £100-350

What to check first

  1. Locate the mode selector switch on the front panel.
  2. Turn the switch to the 'OFF/RESET' position and wait for 5-10 seconds.
  3. Turn the switch back to either 'Hot Water Only' or 'Heating & Hot Water' and wait for the boiler to restart.

Parts commonly replaced

  • Ignition Electrode
  • Printed Circuit Board (PCB)
  • Thermistor

Related codes

Full explanation for Green LED Off, Red LED On
GREEN LED ON every 0.5-secs

Your boiler is in a temporary standby mode because it has detected a minor issue, such as low water pressure or a momentary sensor error.

Medium DIY-safe £0-120

What to check first

  1. Check the pressure gauge on the front of the boiler; if it is below 1 bar, top it up to 1.5 bar using the filling loop.
  2. Ensure the blue mode selector switch is set to the 'ON' or 'DHW' position.
  3. Turn the selector dial to 'Reset' for a few seconds and then back to your desired setting.

Parts commonly replaced

  • Air Pressure Switch
  • Water Pressure Sensor
Full explanation for GREEN LED ON every 0.5-secs
Showing 11–20 of 26
Green LED On, Red LED Off

Your boiler has lost water pressure and has shut itself down as a safety precaution to prevent damage.

High DIY-safe £0-120

What to check first

  1. Locate the filling loop (usually a silver flexible hose) underneath the boiler.
  2. Slowly open the one or two taps/levers on the hose until you hear water flowing.
  3. Watch the pressure gauge until it reaches 1.5 bar, then close the taps tightly.

Parts commonly replaced

  • Filling loop valve
  • Expansion vessel
  • Pressure relief valve
Full explanation for Green LED On, Red LED Off
limit thermostat

Your boiler has detected that it is dangerously hot and has shut itself down to prevent internal damage.

High Engineer only £150-300

Parts commonly replaced

  • Overheat thermostat
  • Pump
  • Diverter valve
  • Primary heat exchanger
Full explanation for limit thermostat
low water pressure

Your boiler has stopped working because the amount of water inside your heating system has dropped below the required level.

High DIY-safe £80-120

What to check first

  1. Locate the external filling loop, which is usually a flexible silver hose under the boiler connecting two pipes.
  2. Open the small valve(s) on the loop to allow mains water into the heating system.
  3. Monitor the pressure gauge on the front of the boiler until the needle reaches the green zone, typically between 1 and 1.5 bar.
  4. Close the valve(s) firmly and ensure the flexible hose is disconnected if required by your specific model.

Parts commonly replaced

  • Filling loop
  • Pressure relief valve
  • Pressure sensor
Full explanation for low water pressure
ON every 0.5-secs

Your boiler is signalling a temporary issue, which is often caused by the water pressure being too low or a blockage in the internal air vents.

High DIY-safe £90-180

What to check first

  1. Check the pressure gauge on the front of the boiler; if it is below 1.0 bar, use the filling loop to top it up to 1.5 bar.
  2. Turn the boiler off at the mains for 30 seconds and then restart it to see if the fault clears.
  3. Ensure your external flue terminal located outside your home is not blocked by debris or leaves.

Parts commonly replaced

  • Air Pressure Switch
  • Pressure Relief Valve
  • Pressure Gauge
Full explanation for ON every 0.5-secs
ON every 0.5-secs (RED LED)

Your boiler has detected a critical internal safety fault and has locked itself down to prevent damage, meaning it will not provide any heating or hot water until a professional engineer repairs it.

High Engineer only £120-300

Parts commonly replaced

  • Pressure switch
  • Fan assembly
  • Limit thermostat
  • PCB
Full explanation for ON every 0.5-secs (RED LED)
primary NTC open/short circuit

Your boiler's temperature sensor is faulty or disconnected, causing the system to stop working because it cannot accurately measure how hot the water is.

High Engineer only £120-200

Parts commonly replaced

  • Primary NTC Thermistor
  • Wiring harness
Full explanation for primary NTC open/short circuit
Red | On every 0.5 second

Your boiler has entered a safety lockout mode due to a critical internal fault or an ignition failure.

High DIY-safe £100-£350

What to check first

  1. Move the mode selector switch to the 'OFF/RESET' position.
  2. Wait approximately 10 seconds.
  3. Move the switch back to either 'Hot Water Only' or 'Heating and Hot Water' and wait for the boiler to attempt to reignite.

Parts commonly replaced

  • Ignition electrode
  • Printed Circuit Board (PCB)
  • Gas Valve
Full explanation for Red | On every 0.5 second
Red LED illuminated

Your boiler has stopped working because the water pressure is too low for the system to run safely.

High DIY-safe £0-80

What to check first

  1. Locate the filling loop (the silver flexible hose) underneath or near the boiler.
  2. Slowly open the one or two taps/valves on the filling loop until you hear water entering the system.
  3. Watch the pressure gauge on the front of the boiler and close the taps once the needle reaches between 1 and 1.5 bar.
  4. Restart or reset the boiler by turning the mode selector switch to 'OFF/RESET' and then back to heating/hot water.

Parts commonly replaced

  • Filling loop valves
  • Pressure gauge
  • Expansion vessel
Full explanation for Red LED illuminated
RED LED ON every 0.5-secs

Your boiler has detected a safety-related issue with its internal components or airflow and has locked itself down to prevent damage.

High DIY-safe £100-350

What to check first

  1. Check that the system water pressure is between 1 and 1.5 bar on the pressure gauge
  2. Turn the mode selector switch to 'OFF/RESET' for a few seconds, then back to the heater or hot water icon
  3. Ensure the external flue terminal is not obstructed by debris or garden growth

Parts commonly replaced

  • Fan
  • Air Pressure Switch
  • Limit Thermostat
  • Condensate Trap

Related codes

Full explanation for RED LED ON every 0.5-secs
RED LED Solid

Your boiler has detected a fault with its internal temperature sensor, preventing it from heating your water and radiators safely.

High Engineer only £90-160

Parts commonly replaced

  • Primary NTC thermistor
  • Wiring harness
Full explanation for RED LED Solid
Showing 21–26 of 26
Red On every 0.5 second

Your boiler has detected a critical internal error and has automatically shut itself down to prevent damage or potential danger.

High Engineer only £150-300

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Wiring harness
  • Overheat thermostat
Full explanation for Red On every 0.5 second
Solid

Your boiler is struggling to accurately measure the temperature of your hot water, which means it may fail to heat the water properly or stop producing it altogether.

High Engineer only £120-200

Parts commonly replaced

  • DHW NTC Thermistor
Full explanation for Solid
Solid (RED LED)

Your boiler has stopped working because it can no longer accurately read the temperature of the water inside the heating system.

High Engineer only £120-220

Parts commonly replaced

  • Primary NTC sensor
  • Wiring harness
Full explanation for Solid (RED LED)
Solid (YELLOW LED)

Your boiler is struggling to accurately measure the temperature of your hot water, which means it may fail to provide hot water or heat it to the wrong temperature.

Medium Engineer only £120-200

Parts commonly replaced

  • DHW NTC thermistor
  • Wiring harness
Full explanation for Solid (YELLOW LED)
water pressure switch

Your boiler has stopped working because it cannot detect enough water inside the system to operate safely.

High DIY-safe £90-180

What to check first

  1. Locate the external filling loop, usually two silver flexible hoses connected to valves underneath the boiler.
  2. Open the valves slowly to allow mains water into the system until the pressure gauge on the front reads between 1.0 and 1.5 bar.
  3. Close both valves tightly and ensure the pressure gauge remains steady.

Parts commonly replaced

  • Water pressure switch
  • Pressure gauge
  • Filling loop
Full explanation for water pressure switch
YELLOW LED Solid

Your boiler has detected a problem with the temperature sensor that controls your hot water, meaning you likely have no hot water or the temperature is inconsistent.

Medium Engineer only £90-160

Parts commonly replaced

  • DHW NTC Thermistor
  • Thermistor Clip

Related codes

Full explanation for YELLOW LED Solid
Status & diagnostic codes

10 operating states & engineer diagnostics

Not faults — these are normal operating states. Tap to expand.

Flashing 8-times a second Status Your boiler is currently protecting itself by performing a self-check on the water temperature sensors to ensure it is heating safely. Green Flashing every 6-seconds Status Your boiler is operating normally and is simply waiting for a command to provide heating or hot water. GREEN LED ON every 6-secs Status Your boiler is in normal standby mode and is simply waiting for you to turn on the heating or hot water. GREEN LED Solid Status Your boiler is working normally and is currently heating your radiators or providing hot water. ON every 0.5-secs (YELLOW LED) Diagnostic Your boiler is currently running in a special diagnostic test mode used by heating engineers, rather than a normal heating mode. ON every 6-secs Status Your boiler is operating normally and is currently in standby mode waiting for a signal for heating or hot water. ON every 6-secs (GREEN LED) Status Your boiler is working perfectly and is simply waiting for a command to provide heating or hot water. Yellow | On every 0.5 second Diagnostic Your boiler is currently in a manual testing mode often used by engineers and is not experiencing a functional fault. YELLOW LED ON every 0.5-secs Diagnostic Your boiler is currently running in a special engineer-only testing mode used to check combustion levels, meaning it is not in its normal operating state. Yellow On every 0.5 second Diagnostic Your boiler has reached its scheduled annual service interval and is reminding you that it is time for a professional maintenance check-up.