Vokera Compact Fault codes & diagnostics

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

Gas
Choose your boiler type

The Compact range comes in 2 types

Pick the one you have. The fault codes, GC numbers and manual differ by type.

25 11 codes · 1 GC number 29 11 codes · 1 GC number
Each model has its own manual A family spans several manuals, one per model or generation. Pick your model above and its page has the manual its fault codes were read from.

The fault code is already on your display

Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →

Severity at a glance

Each cell = one fault code. Hover to identify.
1 Emergency 4 High 1 Medium 5 Low
Just want the most common Vokera Compact faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 11 documented codes

Tap any card for details

Alarm high limit thermostat

Your boiler has shut down because the water inside got dangerously hot, which usually points to a blockage in the system or a failing pump.

High Engineer only £150-£350 Shared across the Compact range

Parts commonly replaced

  • High limit thermostat
  • Circulating pump
  • Automatic bypass valve
  • PCB

Related codes

Full explanation for Alarm high limit thermostat
Alarm safety shutdown and/or internal fault

Your boiler has safely shut itself down due to an internal safety fault and needs to be reset.

High DIY-safe £100-300 Shared across the Compact range

What to check first

  1. Locate the reset button or turn the mode selector to the reset position.
  2. Hold the reset button for about 2 to 5 seconds and release.
  3. Wait to see if the boiler fires up normally; do not repeat this more than twice if it keeps failing.

Parts commonly replaced

  • Printed Circuit Board (PCB)
  • Safety sensor
  • Wiring harness

Related codes

Full explanation for Alarm safety shutdown and/or internal fault
Alarm system water pressure

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

High DIY-safe Shared across the Compact range

What to check first

  1. Locate the filling loop valves underneath your boiler.
  2. Open the valves gently to let water into the system while watching the pressure gauge.
  3. Stop filling when the needle reaches between 1 and 1.5 bar, then close the valves firmly.
  4. Press the reset button on your boiler to clear the fault.

Parts commonly replaced

  • Pressure relief valve
  • Filling loop
  • Pressure sensor

Related codes

Full explanation for Alarm system water pressure
Boiler stand-by

Your boiler is currently in standby mode and waiting for a heating or hot water demand from your thermostat.

Low DIY-safe Shared across the Compact range

What to check first

  1. Check your room thermostat or programmer to ensure it is turned on and set to a higher temperature than the current room temperature.
  2. Verify that the timer or schedule on your heating controls is currently active.
  3. Turn the boiler off at the fused spur, wait 30 seconds, and turn it back on to reset the system.
Full explanation for Boiler stand-by
Fault sensors

Your boiler has detected an issue with its internal temperature sensors and has temporarily stopped working for safety.

High Engineer only £100-£200 Shared across the Compact range

Parts commonly replaced

  • NTC thermistor
  • Temperature sensor
  • Wiring harness
Full explanation for Fault sensors
N/A

Your boiler's temperature sensors are detecting a problem and need to be reset.

Medium DIY-safe £90-180 Shared across the Compact range

What to check first

  1. Turn the boiler off and on again using the reset button or power switch.
  2. Wait a few minutes to see if the error clears.
  3. If the error immediately returns, the internal sensors may be faulty.

Parts commonly replaced

  • NTC thermistor
  • Temperature sensor

Related codes

Full explanation for N/A
Purge cycle mode active

Your boiler is currently running its automated air-clearing cycle, which usually happens after it has just been switched on or refilled.

Low DIY-safe Shared across the Compact range

What to check first

  1. Wait for a few minutes to allow the automated purge cycle to finish on its own.
  2. Do not attempt to turn off or reset the boiler while the lights are flashing.
  3. Check your user manual if the cycle does not complete after 10 minutes.
Full explanation for Purge cycle mode active
Red led fixed

Your boiler has stopped working because it is failing to ignite the flame, which often points to a problem with the gas supply or the exhaust venting system.

Emergency Engineer only £120-250 Shared across the Compact range

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • PCB
  • Flue seal
Full explanation for Red led fixed
Service operation

Your Vokera boiler is indicating that it is time for a scheduled annual service or safety check.

Low Engineer only £70-120 Shared across the Compact range
Full explanation for Service operation
Temporary fault

Your boiler has paused temporarily to protect itself, but it usually resets automatically once the issue clears.

Low DIY-safe Shared across the Compact range

What to check first

  1. Wait a few minutes to see if the boiler resets itself automatically
  2. Switch the boiler off at the fused spur or mains supply, wait 30 seconds, and turn it back on
  3. Check that your hot water taps and heating controls are calling for heat normally
Full explanation for Temporary fault
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