Vokèra A03 fault codewhat it means and how to fix it
The appliance cannot confirm the fan is running correctly, so it will not permit the burner to light. This needs an engineer.
Take care
Get a Gas Safe registered engineer to look at your Vokèra A03
We do not pass enquiries to a repair firm, so there is no form here. Find a Gas Safe registered engineer through the Gas Safe Register, and ask to see their registration card when they arrive — it is the register, not the van, that tells you they are qualified.
What A03 means
The fan clears combustion products out through the flue, and no condensing appliance will open its gas valve until it has proved the fan is turning at the commanded speed. A03 means that proof failed. The interlock is absolute: there is no way to run the appliance around it, and there should not be. In service the two realistic causes are a fan that has worn out and a flue that is obstructed, and they are worth separating because they cost very different amounts.
Fan bearings dry out after roughly eight to twelve years and usually give warning first, as a rumble or grind on start-up that the household gradually stops hearing. A flue obstruction — a nest, leaf litter, or render forced into the terminal during building work — changes the resistance the fan is working against, which throws the speed reading even though the fan itself is perfectly healthy. Replacing a good fan because nobody checked the flue is a common and avoidable expense.
What causes it
| Cause | What is actually happening | How likely |
|---|---|---|
| Fan bearings worn | The dominant cause on appliances beyond about eight years. Usually preceded by months of increasing noise on start-up. | Common |
| Flue blocked or obstructed | Nesting birds, debris, or building materials in the terminal. Changes fan loading enough to fail the speed check. | Occasional |
| Fan wiring or connector fault | The fan turns but the speed signal never reaches the board. Cheap if that is genuinely the whole problem. | Occasional |
| Control board misreading the signal | Diagnosed last, after the fan and the flue have both been ruled out properly. | Rare |
Can you fix it yourself?
Stop — this needs an engineer
What it costs to fix
Typical repair cost
£180–£420
A fan assembly is typically £280 to £420 fitted. A flue clearance or a connector repair is a call-out charge of £80 to £140.
Typical UK prices including parts and labour, updated September 2026. Your quote may differ.
Own this appliance and had this code? . Nothing is published until a person has read it.
Related Vokèra fault codes
- A09Get it checkedThe flue gas sensor has recorded a temperature above the safe limit, or the sensor itself has failed. Either way the appliance stops.Related: fan and flue
- A01Get it checkedThe burner failed to light and the appliance has locked out. Check the gas supply and, in cold weather, the condensate pipe before calling anyone.Related: same brand
- A04Usually simple to fixSystem water pressure is below the minimum the appliance will run at. Topping the system back up to 1.2 bar normally clears it straight away.Related: same brand
- A02Get it checkedThe safety limit thermostat has tripped on overheat. In practice this nearly always means water has stopped circulating properly.Related: same brand
- A11Stop — call an engineerThe appliance is detecting a flame when there should not be one. Turn it off at the fused spur and get a Gas Safe engineer out.Related: same brand
- A07Get it checkedThe primary flow sensor is reading out of range or has failed. The appliance stops because it can no longer tell how hot it is running.Related: same brand
Own a Vokèra boiler? Save it and its codes come first next time.
Related guides
Common questions about Vokèra A03
Can I check anything myself before booking someone?
Look at the flue terminal from the ground in daylight and note whether there is anything obviously in it. That observation is genuinely useful. Do not reach into it, and do not remove the appliance casing.
The boiler has been noisy for months. Is that connected?
Almost certainly. A fan that grumbles on start-up and then quietens as it comes up to speed is a bearing on its way out, and this code is the end of that process.
Other lists mention A05 as a second Vokèra fan code. Is that real?
Not in anything Vokèra publish. Their Vision tables run A01 to A04, then A06 to A09, A11 and A77, with no A05 anywhere, and the fan appears once as A03 "fan tacho signal fault". The later ranges have a single fan code too — AL34 on the Mynute, A30 on the Easi-heat i, E030 on the Vision Plus. This page used to draw a distinction between A03 and a supposed A05 and that distinction has been removed, because it could not be found in the manufacturer's documentation.
Technical review
Not reviewed by an engineer
No engineer has read this page. Severity follows what the manufacturer publishes, and we would rather tell you that than let a byline imply a sign-off.
Sources and how we verified this
We establish the facts from the sources below and then write the explanation ourselves. We do not copy manufacturer wording and we do not host their manuals.
- Manufacturer technical and service documentation
This page has not been reviewed by an engineer, and we would rather tell you that than imply otherwise. The severity rating follows what the manufacturer publishes: where they say isolate the appliance and call someone, so do we.