Vokera Vision Fault codes & diagnostics

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

Combi Gas
GC Number 47-364-11
Download the Vokera Vision manualThe official installation and service manual (PDF), the document these fault codes were read from. PDF

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Severity at a glance

Each cell = one fault code. Hover to identify.
1 Emergency 8 High 4 Low

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
47-364-11 Vision 30C 2012–present

Appliance names and production years are taken from the UK Product Characteristics Database (the SAP/SEDBUK register). Where a GC number is also printed in this model's own manufacturer manual, both sources were checked to agree.

All 13 documented codes

Tap any card for details

_CL

Your boiler has reached its programmed time limit for a scheduled service and is prompting you to book a professional engineer to check the system.

Low Engineer only £90-140

Parts commonly replaced

  • None (Service required)
_St

Your boiler has entered a temporary standby mode, which often happens if the system is waiting for the room thermostat to request heating or a hot tap to be opened.

Low DIY-safe

What to check first

  1. Check your room thermostat is turned up high enough to request heat
  2. Ensure your heating programmer is set to 'ON'
  3. Check if the boiler begins working once you turn on a hot water tap
A01

Your boiler has failed to light the flame needed to produce heat or hot water, and it has locked itself out for safety.

High Engineer only £120-250

Parts commonly replaced

  • Ignition electrode
  • Gas valve
  • PCB

Related codes

A02

Your boiler has detected that it is running too hot and has safely shut itself down to prevent damage.

High Engineer only £120-250

Parts commonly replaced

  • Limit thermostat
  • NTC thermistor
  • Pump
  • Heat exchanger

Related codes

A03

Your boiler is struggling to detect that the internal fan, which clears exhaust gases, is spinning correctly.

High Engineer only £150-£250

Parts commonly replaced

  • Fan assembly
  • Printed Circuit Board (PCB)
  • Wiring harness

Related codes

A04

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

High DIY-safe £80-150

What to check first

  1. Locate the filling loop (a flexible metal hose) underneath your boiler or near your airing cupboard.
  2. Open the valves on the filling loop slowly to let water into the system.
  3. Watch the pressure gauge on the front of the boiler until the needle reaches the green zone (usually between 1 and 1.5 bar).
  4. Close both valves tightly to stop the flow of water.

Parts commonly replaced

  • Pressure relief valve
  • Expansion vessel
  • Filling loop

Related codes

A06

Your boiler is temporarily unable to accurately measure the temperature of your water or heating system due to a faulty sensor.

High Engineer only £120-250

Parts commonly replaced

  • DHW thermistor
  • Primary flow thermistor

Related codes

A07

Your boiler has temporarily stopped working because it has detected that the water inside is getting much too hot.

High Engineer only £120-250

Parts commonly replaced

  • Primary thermistor (flow NTC sensor)
  • Automatic bypass valve
  • Circulating pump

Related codes

A08

Your boiler has detected that the water temperature returning to it is unusually high or that the sensors are not reading the temperature correctly, causing it to shut down to prevent damage.

High Engineer only £120-220

Parts commonly replaced

  • Return NTC thermistor
  • PCB

Related codes

A09

Your boiler has detected that the exhaust gases are becoming dangerously hot, so it has shut down to prevent damage or safety risks.

Emergency Engineer only £150-300

Parts commonly replaced

  • Flue thermistor
  • Heat exchanger
  • Main PCB

Related codes

A77

Your boiler's internal computer is receiving an unexpected temperature reading from a sensor, which has caused it to stop working for safety reasons.

High Engineer only £120-250

Parts commonly replaced

  • NTC temperature sensor
  • Wiring harness
  • Printed Circuit Board

Related codes

ACO

Your boiler has reached its programmed time limit and is simply reminding you that a routine safety service is now due.

Low Engineer only £90-140

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