BoilerFaultCodes _St
Your boiler has entered a temporary pause mode, usually because it has reached its set temperature or is completing a standard safety cycle, and it should resume normal operation shortly.
Vokera Vision Combi 25C / 30C Fault codes & diagnostics
10 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Combi Natural Gas 25-30 kW 2012 onwards Discontinued
GC Number 47-364-10
Replaced by: Vision Plus
Download the Vokera Vision Combi 25C / 30C manual
PDF
Versions & GC numbers
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. 8 High
1 Medium
1 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 |
|---|---|---|
| 47-364-10 | Vision 25C | 2012–present |
Just want the most common Vokera Vision Combi 25C / 30C faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes
All 10 documented codes
Tap any card for details
A01 Your boiler has failed to light the flame needed to heat your home's water, which means both your heating and hot water are currently unavailable.
Your boiler has failed to light the flame needed to heat your home's water, which means both your heating and hot water are currently unavailable.
Parts commonly replaced
- Ignition electrode
- Gas valve
- PCB (Printed Circuit Board)
Related codes
A02 Your boiler has detected that the water inside the system has become dangerously hot and has safely shut itself down to prevent damage.
Your boiler has detected that the water inside the system has become dangerously hot and has safely shut itself down to prevent damage.
Parts commonly replaced
- Limit thermostat
- Primary flow sensor
- Pump
Related codes
A03 Your boiler has detected that the internal fan responsible for safely exhausting fumes is not rotating correctly or reporting its speed, so it has shut down to keep you safe.
Your boiler has detected that the internal fan responsible for safely exhausting fumes is not rotating correctly or reporting its speed, so it has shut down to keep you safe.
Parts commonly replaced
- Fan assembly
- Wiring harness
- PCB
Related codes
A04 Your boiler has stopped working because the water pressure inside the heating system has dropped too low to operate safely.
Your boiler has stopped working because the water pressure inside the heating system has dropped too low to operate safely.
What to check first
- Locate the external filling loop (a flexible silver hose) underneath the boiler.
- Open the small black or chrome valve taps attached to the loop until you hear water entering the system.
- Watch the pressure gauge on the front of the boiler until the needle reaches the green zone, typically between 1.0 and 1.5 bar.
- Close both valves tightly and ensure the pressure remains steady.
Parts commonly replaced
- Filling loop
- Pressure relief valve
- Pressure transducer
Related codes
A06 Your boiler is having trouble detecting the temperature of the water for your taps and shower, which means the hot water may be inconsistent or stop working altogether.
Your boiler is having trouble detecting the temperature of the water for your taps and shower, which means the hot water may be inconsistent or stop working altogether.
Parts commonly replaced
- DHW NTC thermistor
Related codes
A07 Your boiler has detected that the water inside the heating system is getting too hot or that the temperature sensors aren't reading correctly, so it has safely shut itself down to prevent damage.
Your boiler has detected that the water inside the heating system is getting too hot or that the temperature sensors aren't reading correctly, so it has safely shut itself down to prevent damage.
Parts commonly replaced
- Primary NTC Thermistor
- PCB
Related codes
A08 Your boiler has detected that the water temperature coming back into the unit is being read incorrectly or is running hotter than it should be, causing the system to stop working safely.
Your boiler has detected that the water temperature coming back into the unit is being read incorrectly or is running hotter than it should be, causing the system to stop working safely.
Parts commonly replaced
- Return NTC Thermistor
- Control PCB
Related codes
A09 Your boiler has detected that the temperature of the exhaust gases leaving the unit is higher than it should be, so it has shut itself down to stay safe.
Your boiler has detected that the temperature of the exhaust gases leaving the unit is higher than it should be, so it has shut itself down to stay safe.
Parts commonly replaced
- Flue gas sensor
- NTC thermistor
- Main PCB
Related codes
A77 Your boiler is struggling to accurately monitor its own internal water temperature, so it has stopped working to prevent potential overheating.
Your boiler is struggling to accurately monitor its own internal water temperature, so it has stopped working to prevent potential overheating.
Parts commonly replaced
- NTC temperature sensor
- Wiring harness
Related codes
Status & diagnostic codes 3 operating states & engineer diagnostics
Not faults — these are normal operating states. Tap to expand.
3 operating states & engineer diagnostics
Not faults — these are normal operating states. Tap to expand.
_CL Diagnostic Your boiler has reached its programmed time for a routine annual service and is simply reminding you that a qualified professional should inspect and maintain it. ACO Diagnostic Your boiler has reached its programmed time for a routine annual safety service and is alerting you that maintenance is now due. Adj Diagnostic Your boiler is currently undergoing an automatic internal calibration process, which usually happens during setup or after specific adjustments.