Vokera Maxim Fault codes & diagnostics

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

Combi Natural Gas 25-29 kW 2016 onwards Discontinued
GC Numbers 47-364-3147-364-32
Download the Vokera Maxim 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 →

Severity at a glance

Each cell = one fault code. Hover to identify.
5 High 1 Low
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
47-364-31 Maxim 25 2016–present
47-364-32 Maxim 29 2016–present
Just want the most common Vokera Maxim faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes

All 6 documented codes

Tap any card for details

Alarm high limit thermostat

Your boiler has detected that it has become too hot and has automatically shut down to prevent damage or overheating.

High Engineer only £120-250

Parts commonly replaced

  • High limit thermostat
  • Pump
  • Diverter valve
  • PCB
Full explanation for Alarm high limit thermostat
Alarm system water pressure

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

High DIY-safe £80-120

What to check first

  1. Locate the filling loop (a flexible metal hose) underneath your boiler.
  2. Open the valves on the hose to let mains water into the system until the pressure gauge reads between 1 and 1.5 bar.
  3. Close the valves tightly and press the reset button on your boiler.

Parts commonly replaced

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

Your boiler has detected that one of its internal temperature sensors is providing unreliable information, so it has shut down to prevent overheating.

High Engineer only £120-220

Parts commonly replaced

  • NTC thermistor
  • Wiring harness

Related codes

Full explanation for Fault sensors
low-pressure fault code

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

High DIY-safe £80-120

What to check first

  1. Locate the external filling loop, which is a silver braided hose connected between two valves underneath your boiler.
  2. Slowly open both valves on the filling loop to allow cold mains water to enter the system.
  3. Watch the pressure gauge on the front of the boiler until the needle reaches the green zone, ideally around 1.0 to 1.5 bar, then securely close both valves.

Parts commonly replaced

  • Filling loop
  • Pressure relief valve
  • Pressure transducer
Full explanation for low-pressure fault code
Red led fixed

Your boiler has stopped working because it cannot safely ignite or prove a flame, meaning you currently have no heating or hot water.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Printed Circuit Board (PCB)
  • Gas valve
  • Flue seal
Full explanation for Red led fixed
Temporary fault

Your boiler is experiencing a minor, fleeting glitch that has caused it to pause operation briefly.

Low DIY-safe

What to check first

  1. Locate the reset button on the front control panel
  2. Press and hold the reset button for 5 seconds
  3. Wait up to 5 minutes to see if the burner ignites and the fault clears
Full explanation for Temporary fault
Status & diagnostic codes

5 operating states & engineer diagnostics

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

Boiler stand-by Status Your boiler is currently switched off or waiting for a signal to start, meaning it is not active but is operating normally. DHW pre-heat function Status Your boiler is currently set to keep its internal water store warm for faster hot water delivery, but this is a settings preference rather than a breakdown. Flame ON Status Your boiler is signalling that the burner is currently lit and operating normally as it provides heating or hot water. Purge cycle mode active Status Your boiler is simply running a routine 5-minute safety self-test to clear any trapped air from the system before it restarts. Service operation Diagnostic Your boiler is simply reminding you that it is due for its annual safety check and maintenance service.