Vokera Excel Fault codes & diagnostics

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

Combi Natural Gas 25-29 kW 2013-present
GC Numbers 47-364-1247-364-1347-364-6547-364-66
Download the Vokera Excel manual The official installation & service manual (PDF) — the exact document these fault codes were verified against. PDF

The fault code is already on your display

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

Versions & GC numbers

Which version do you have?

The GC number on your boiler's data badge identifies the exact appliance and production years, as recorded in the UK Product Characteristics Database.

GC number Appliance (register name) Produced
47-364-12 Excel 25 2013–present
47-364-13 Excel 29 2013–present
47-364-65 EXCEL-i 25C 2021–present
47-364-66 EXCEL-i 30C 2022–present
Just want the most common Vokera Excel faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 5 documented codes

Tap any card for details

Alarm high limit thermostat

Your boiler has detected that the water inside it has become dangerously hot and has shut down to prevent damage or overheating.

High Engineer only £120-250

Parts commonly replaced

  • Limit Thermostat
  • NTC Sensor
  • Pump
  • Diverter Valve
Full explanation for Alarm high limit thermostat
Alarm system water pressure

Your boiler has detected that the water pressure in your heating system is either too low or too high for it to operate safely.

High DIY-safe £80-150

What to check first

  1. Locate the filling loop (usually a silver braided hose with one or two valves) underneath the boiler.
  2. Open the valve(s) slowly to allow water into the system until the pressure gauge on the front of the boiler reads between 1.0 and 1.5 bar.
  3. Close the valve(s) tightly to stop the flow of water.

Parts commonly replaced

  • Pressure relief valve
  • Pressure sensor
  • Expansion vessel
Full explanation for Alarm system water pressure
Fault sensors

Your boiler has detected that one of its internal monitoring components is providing an incorrect reading, so it has shut down to ensure your safety.

High Engineer only £120-250

Parts commonly replaced

  • NTC Thermistor
  • Flow Temperature Sensor
  • Wiring Harness
Full explanation for Fault sensors
Red led fixed

Your boiler has stopped working because it cannot light itself, which usually indicates an issue with the gas flow, the air ventilation, or the electrical connection.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • PCB
  • Flue fan
Full explanation for Red led fixed
Temporary fault

Your boiler has detected a brief, minor glitch and is attempting to sort itself out automatically.

Low DIY-safe

What to check first

  1. Wait five minutes to see if the boiler resumes normal operation automatically.
  2. If it persists, turn the boiler off at the fused spur or mains switch.
  3. Wait 30 seconds before turning the power back on to force a system reset.
Full explanation for Temporary fault
Status & diagnostic codes

4 operating states & engineer diagnostics

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

Boiler stand-by Status Your boiler is currently in standby mode and is working exactly as it should, waiting for a signal from your heating or hot water controls. Flame ON Status Your boiler is detecting a flame inside when it should be turned off, which indicates a serious control error. Purge cycle mode active Status Your boiler is currently performing an automatic safety check to clear trapped air from the system before it resumes normal operation. Service operation Diagnostic Your boiler has reached its programmed time limit and is simply reminding you that it is due for its annual safety service.
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