BoilerFaultCodes P blinking
Your boiler is simply performing a standard procedure to keep a small amount of water warm, allowing it to provide hot water to your taps more quickly.
Vokera Unica i36 Fault codes & diagnostics
18 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Combi Natural Gas 2014-present
GC Number 47-364-16
Download the Vokera Unica i36 manual
PDF
This boiler uses LED flash patterns
Count the flashes in one repeating group before the pause. That number is your fault code. Do not reset until you have noted it. How to read fault codes →
Severity at a glance
Each cell = one fault code. Hover to identify. 2 Emergency
8 High
8 Low
Fault codes
All 18 documented codes
Tap any card for details
LED / flash-pattern codes
Digital codes
_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.
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.
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.
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.
What to check first
- Check your room thermostat is turned up high enough to request heat
- Ensure your heating programmer is set to 'ON'
- Check if the boiler begins working once you turn on a hot water tap
A01 Your boiler has tried to start up several times but failed to ignite the gas safely, so it has locked itself out to prevent any issues.
Your boiler has tried to start up several times but failed to ignite the gas safely, so it has locked itself out to prevent any issues.
What to check first
- Check if your gas supply is working by testing another gas appliance like a hob.
- Locate the reset button on your Vokera Unica i32 and hold it down for 3 to 5 seconds.
- Check that your prepaid gas meter has credit if you use one.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Printed circuit board (PCB)
Related codes
A02 Your boiler has detected that it is running too hot and has safely shut itself down to prevent damage.
Your boiler has detected that it is running too hot and has safely shut itself down to prevent damage.
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.
Your boiler is struggling to detect that the internal fan, which clears exhaust gases, is spinning correctly.
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.
Your boiler has stopped working because the water pressure inside the heating system has dropped too low.
What to check first
- Locate the filling loop (a flexible metal hose) underneath your boiler or near your airing cupboard.
- Open the valves on the filling loop slowly to let water into the system.
- Watch the pressure gauge on the front of the boiler until the needle reaches the green zone (usually between 1 and 1.5 bar).
- 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 struggling to detect the temperature of your hot water, so it has stopped providing it to prevent the system from overheating.
Your boiler is struggling to detect the temperature of your hot water, so it has stopped providing it to prevent the system from overheating.
Parts commonly replaced
- DHW NTC thermistor sensor
- Wiring harness
Related codes
A07 Your boiler is not reading its internal water temperature correctly, causing it to shut down to prevent overheating.
Your boiler is not reading its internal water temperature correctly, causing it to shut down to prevent overheating.
Parts commonly replaced
- Flow NTC Thermistor
- Wiring harness
Related codes
A08 Your boiler has temporarily stopped working because it cannot accurately read the temperature of the water returning to it.
Your boiler has temporarily stopped working because it cannot accurately read the temperature of the water returning to it.
Parts commonly replaced
- Return thermistor
- NTC sensor
- Wiring harness
Related codes
A09 Your boiler has temporarily stopped working because the exhaust area has become too hot, which is a built-in safety measure to prevent damage.
Your boiler has temporarily stopped working because the exhaust area has become too hot, which is a built-in safety measure to prevent damage.
Parts commonly replaced
- Flue thermistor
- Main PCB
- Heat exchanger
Related codes
A11 Your boiler has detected a flame inside the unit when it was supposed to be turned off, so it has safely shut itself down to prevent a hazard.
Your boiler has detected a flame inside the unit when it was supposed to be turned off, so it has safely shut itself down to prevent a hazard.
Parts commonly replaced
- Gas valve
- PCB (Printed Circuit Board)
- Flame rectification electrode
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.
Your boiler's internal computer is receiving an unexpected temperature reading from a sensor, which has caused it to stop working for safety reasons.
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.
Your boiler has reached its programmed time limit and is simply reminding you that a routine safety service is now due.
Adj
Your boiler is currently recalibrating its internal settings to ensure it operates efficiently after a recent change or power cycle.
Flame ON
Your boiler is signalling that the burner is on, which is a normal operational status rather than a fault.
Hours Your boiler is perfectly healthy and is simply resting until you turn on a tap or adjust your heating.
Your boiler is perfectly healthy and is simply resting until you turn on a tap or adjust your heating.
What to check first
- No action required
- This is the normal state when the boiler is waiting for a demand for hot water or heating
P
Your boiler is simply performing its normal routine of keeping water warm inside so you get hot water faster when you turn the tap on.
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