Vokera Compact 25 Fault codes & diagnostics

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

Combi Natural Gas 25 kW Discontinued

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.
6 High 1 Medium 2 Low
Just want the most common Vokera Compact 25 faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 9 documented codes

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Check JP1

Your boiler has detected an internal configuration error, likely due to a loose link on the main computer board, which is preventing it from starting up correctly.

High Engineer only £120-250

Parts commonly replaced

  • PCB (Printed Circuit Board)
  • Wiring harness
Full explanation for Check JP1
GREEN LED On every 0.5-secs

Your boiler has paused because it has detected a temporary issue, likely due to low water pressure or an intake problem, and is waiting for the condition to clear.

High DIY-safe £0-180

What to check first

  1. Check the pressure gauge on the front of the boiler; it should be between 1 and 1.5 bar.
  2. If the pressure is too low, use the filling loop valves to top up the system.
  3. Ensure the external flue terminal is not blocked by leaves, debris, or snow.
  4. Turn the mode selector switch to 'OFF/RESET' for a few seconds and then back to 'ON'.

Parts commonly replaced

  • Air Pressure Switch
  • Filling Loop
  • Fan
Full explanation for GREEN LED On every 0.5-secs
GREEN LED Solid

Your boiler is working normally and is currently heating your home or providing hot water.

Low DIY-safe

What to check first

  1. No action required as this is normal operation
  2. Check your thermostat if the heating is on when you do not want it to be

Related codes

Full explanation for GREEN LED Solid
Pressure < 0.5 bar

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

High DIY-safe £80-150

What to check first

  1. Locate the filling loop, which is usually a flexible silver hose with one or two valves underneath the boiler.
  2. Slowly open the valve(s) to let mains water into the system until the pressure gauge needle sits between 1.0 and 1.5 bar.
  3. Close the valve(s) tightly and check that the boiler restarts.

Parts commonly replaced

  • Filling loop
  • Pressure relief valve
  • Pressure gauge
  • Expansion vessel
Full explanation for Pressure < 0.5 bar
RED LED On every 0.5-secs

Your boiler has encountered a permanent safety lockout and has stopped working to protect itself.

High DIY-safe £90-320

What to check first

  1. Check if the water pressure gauge is between 1 and 1.5 bar
  2. Rotate the mode selector switch to 'OFF/RESET' for 5 seconds
  3. Switch the dial back to the previous setting to see if the boiler restarts

Parts commonly replaced

  • Primary NTC Thermistor
  • Ignition Electrode
  • Fan
  • Printed Circuit Board (PCB)

Related codes

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

Your boiler has likely overheated, causing a safety switch to trip and shut down the system to prevent damage.

High DIY-safe £90-180

What to check first

  1. Check that your radiator valves are open to allow water to flow.
  2. Ensure the system pressure is between 1 and 1.5 bar on the pressure gauge.
  3. Wait for the boiler to cool down, then turn the mode selector switch to 'OFF/RESET' for a few seconds before switching it back to 'ON'.

Parts commonly replaced

  • Overheat Limit Thermostat
  • Circulation Pump
  • Thermistor (NTC Sensor)
Full explanation for RED LED Solid
Reset light illuminated

Your boiler has stopped working because it couldn't light the flame correctly or has detected it is running too hot.

High Engineer only £120-200

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • PCB
  • NTC thermistor
Full explanation for Reset light illuminated
YELLOW LED Solid

Your boiler has entered a test mode and is currently unable to provide normal heating or hot water.

Medium DIY-safe £60-120

What to check first

  1. Locate the selector dial on the front control panel.
  2. Turn the dial to the 'OFF/RESET' position.
  3. Wait five seconds, then turn the dial back to your desired 'Heating and Hot Water' setting.

Parts commonly replaced

  • Control Knob
  • Main Printed Circuit Board (PCB)

Related codes

Full explanation for YELLOW LED Solid