The most common Vokera boiler error codes include A01 for ignition failure, A04 showing low system pressure, A03 for fan problems, and sensor faults like A07 or A09. These often appear because of everyday things such as a drop in water pressure or a blocked pipe in winter, but repeated codes can point to a boiler that is getting older and less reliable.
If you are a homeowner or landlord anywhere across the North West, Yorkshire and the Midlands, spotting these codes early can save you a lot of hassle. The good news is that most issues are straightforward to understand and sort.
Vokera Boiler Error Codes: A Quick Overview
Vokera boiler error codes give you a clear snapshot of what is happening inside your appliance so you can take the right action and keep your home warm and comfortable.
| Error Code | Description |
|---|---|
| _St | Autostop for safety |
| _CL | Call for service |
| A01 | Ignition failure flame not sensed |
| A02 | Limit thermostat fault |
| A03 | Fan fault |
| A04 | Insufficient system water pressure |
| A06 | Domestic hot water thermistor fault |
| A07 | Primary flow thermistor fault (temp too high) |
| A08 | Return thermistor fault (temp too high) |
| A09 | Flue thermistor or counter fault |
| A11 | False flame detected |
| A77 | Low temperature thermostat fault |
Vokera Boiler Error Codes: Causes & How to Fix
Vokera boiler error codes each highlight a particular part of your system that needs checking so you can fix the issue safely and get your heating running smoothly again.
Error Code A01: Ignition Failure
Vokera boiler error code A01 means the appliance has tried to light the burner but cannot sense a flame, so it has shut down for safety and left you without heating or hot water.
This fault usually happens when the gas supply is interrupted, the ignition electrodes are dirty, there is a problem with the gas valve, or the flame sensor has become worn after years of use.
Here is how to fix it step by step:
- Make sure your gas meter and the boiler gas isolator valve are turned on fully.
- Press the reset button on the boiler once and watch to see if it tries to ignite.
- If it fails again, turn the boiler off at the mains for thirty seconds then try resetting once more.
- Check that other gas appliances in the house are working to rule out a wider supply issue.
- Do not keep resetting if the code returns straight away, as this can damage parts.
- Contact a Gas Safe registered engineer right away for a proper inspection and cleaning of the electrodes or gas valve.
Error Code A04: Low Water Pressure
The A04 error code A04 on your Vokera boiler tells you the system water pressure is too low for safe operation, which is one of the most frequent faults we see in homes around the North West and Yorkshire.
It is normally caused by a small leak in the pipework or radiators, air in the system, or the pressure dropping naturally over time as water cools.
Follow these steps to fix it:
- Look at the pressure gauge on the front of the boiler.
- If it reads below one bar, locate the filling loop (the flexible silver hose underneath).
- Open both valves slowly until the gauge reaches between one and one point five bar, then close them firmly.
- Inspect visible pipes and radiator valves for any signs of leaks or damp.
- Press the reset button and test the heating.
- If the pressure falls again within a day or two, arrange a professional leak check straight away.
Error Code A03: Fan Fault
The A03 error code appears when the fan that clears exhaust gases through the flue is not working properly, so the boiler locks out to keep everything safe.
Common reasons include a seized fan motor, a blocked flue outlet, or loose wiring that develops after several years of daily running.
Safe troubleshooting steps are:
- Switch the boiler off at the mains.
- Check the flue terminal outside for any obvious debris or bird nests without touching anything yourself.
- Restart the boiler and listen for the fan spinning up.
- If the code returns quickly, call a Gas Safe engineer to test and replace the fan unit.
Error Code A02: Limit Thermostat Fault
The A02 error code A02 signals that the limit thermostat has detected the water temperature rising too high and has shut the boiler down to prevent damage.
It can be triggered by poor water circulation, air trapped in the radiators, a sluggish pump, or a build up of sludge in older systems.
Try these steps:
- Turn the boiler off and allow it to cool for fifteen minutes.
- Bleed all radiators starting from the highest in the house.
- Check system pressure and top it up if needed.
- Restart and see if the code clears.
- Persistent A02 faults usually need an engineer to check the pump and thermostat.
Error Code A07: Primary Flow Thermistor Fault
The A07 error code means the sensor measuring the temperature of water leaving the boiler has detected a problem, often showing the temperature is higher than expected.
Causes include a faulty sensor, poor flow due to a blocked heat exchanger, or wiring issues that appear as the boiler ages.
The fix process is:
- Note the exact code and turn the boiler off at the mains for five minutes.
- Restart and monitor whether the code returns immediately.
- If it does, a qualified engineer must test the thermistor and replace it if necessary.
- Avoid using the heating until it is checked to prevent further strain.
Error Code A09: Flue Thermistor Fault
The A09 error code A09 indicates a fault with the sensor in the flue or that the boiler has reached a set number of condensing hours and needs attention.
It is often linked to a blocked condensate pipe in cold weather, a faulty flue sensor, or simply the need for a full service.
Here is what to do:
- If it is freezing outside in the Midlands or Yorkshire, gently thaw any external condensate pipe with warm water.
- Reset the boiler after checking.
- If the code stays on, book a service so an engineer can clean the system and test the sensor.
Error Code A11: False Flame
The A11 error code shows that the boiler is detecting a flame when it should not be, which is a safety lockout.
This can happen because of a dirty flame sensor, a leaking gas valve, or electrical interference.
Safe steps include:
- Power the boiler off completely for thirty seconds.
- Reset and observe the display.
- If it returns, stop using the appliance and call a Gas Safe engineer immediately.
Persistent Vokera boiler error codes often mean your current appliance is struggling and could lead to bigger repair bills or a complete breakdown when you need warmth most.
Recurring Vokera Error Codes? It May Be Time for a More Reliable Boiler
If the same Vokera boiler error codes keep appearing, repeated repairs can quickly become expensive and frustrating. Persistent faults are often a sign that key components are wearing out or that the boiler is nearing the end of its lifespan. Upgrading to a modern, energy-efficient boiler can improve reliability, lower running costs, and give you dependable heating and hot water with the reassurance of a long manufacturer warranty.
At Clever Energy Boilers, we provide professional boiler installation across the North West, Yorkshire, and the Midlands, with honest advice and no-pressure quotes. Whether you need a replacement for your home or a dependable heating solution for a rental property, our team can help you choose the right boiler and install it to the highest standard.
Get your free boiler quote today.
Frequently Asked Questions
How long can a Vokera boiler last before error codes become more frequent?
Most Vokera boilers give reliable service for ten to fifteen years with annual servicing, but after eight years many homeowners and landlords notice codes appearing more often as parts start to wear.
Do I need a Gas Safe engineer for every single Vokera boiler error code?
Not always. Simple pressure top ups and bleeding radiators are safe for you to do yourself, but anything involving gas, the fan or sensors must be handled by a qualified Gas Safe registered professional to stay safe and legal.
Can hard water in the Midlands cause more Vokera boiler error codes?
Yes, limescale build up from hard water areas can affect sensors and the heat exchanger, leading to thermistor faults like A07 or A08. Fitting a scale reducer or inhibitor during installation helps prevent this.
What happens if I ignore a recurring Vokera boiler error code?
Ignoring repeated codes can lead to higher gas bills, reduced efficiency, and in some cases unsafe operation. For landlords it could also breach gas safety regulations and affect your tenancy compliance.
Is it better to repair or replace a Vokera boiler that is seven years old?
If the boiler is seven years old and the repair cost is more than half the price of a new model, replacement is usually the smarter choice. A new energy efficient boiler pays for itself through lower running costs and gives you a fresh warranty.
