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Last updated: 11th February, 2024


Vokera Boiler Error Codes - How To Fix

Vokera Boiler Error Codes - How To Fix

Key takeaways

  • Understanding Vokera boiler error codes enables swift problem identification.
  • Homeowners can perform some initial troubleshooting steps for minor issues.
  • Professional intervention by a Gas Safe-registered engineer is essential for technical faults.

Familiarising yourself with common Vokera fault codes and their meanings can be crucial in swiftly addressing and resolving boiler issues, ensuring minimal disruption to your comfort.

Operating a Vokera boiler in your home means enjoying efficient heating and hot water—until an error code appears. These codes signify specific issues ranging from minor sensor faults to more severe problems requiring professional attention. 

Familiarising yourself with common Vokera fault codes and their meanings can be crucial in swiftly addressing and resolving boiler issues, ensuring minimal disruption to your comfort.

Initial troubleshooting steps can often be taken by homeowners before seeking expert help. For example, a flashing red light indicates the system is in fault and lockout mode, typically due to a persistent issue that needs resolving to restore function. 

Some issues, like a fan error indicated by code A03, are more technical and necessitate the assistance of a Gas Safe-registered engineer. It's imperative to address these faults promptly to prevent potential safety risks or further damage to the boiler.

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Gas Safe Engineers

While some error codes are straightforward enough to be identified and fixed by homeowners, we always advise contacting a Gas Safe engineer to assess the situation and carry out any repairs necessary.

All of iHeat’s engineers are fully qualified and Gas Safe, ensuring a swift and safe installation.

General Error Codes:

_St - Autostop

Indicates the boiler has automatically stopped.

_CL - Call for Service

A general alert to contact service personnel.

N/A - Flame On

Indicates that the flame is currently active.

P - Preheating Function Active

Shows that the preheating function is operational.

P Blinking - Preheating Function Running

Indicates the preheating function is in progress.

Hours - Stand-by

The boiler is in standby mode.

— - Off

The boiler is turned off.

A Series Error Codes:

A01 - Ignition Failure

The flame is not sensed, indicating an internal fault.

A02 - Limit Thermostat Fault

Problem detected with the limit thermostat.

A03 - Fan Fault

Indicates an issue with the boiler's fan.

A04 - Insufficient System Water Pressure

Water pressure in the system is too low.

A06 - DHW Thermistor Fault

Domestic hot water thermistor has an issue.

A07 - Primary Flow Thermistor Fault

Water temperature is excessively high.

A08 - Return Thermistor Fault

High temperature detected in return water.

A09 - Flue Thermistor Fault

Issue with the flue thermistor or its counter.

A11 - False Flame

Erroneous flame detection.

A77 - Low Temperature Thermostat Fault

Problem with the low-temperature thermostat.

Vokera Mynute Boiler Error Codes:

AL10, AL20, AL21, AL26, AL28, AL34

Suggests resetting the boiler; if persistent, contact a heating engineer.


Check and refill system pressure; reset boiler, contact engineer if persistent.


Similar to AL40, with emphasis on refilling and contacting an engineer if repeated.

AL52, AL55, AL60, AL71, AL73, AL74, AL79

Advises contacting a heating engineer.

AL74, AL79

Recommends a reset, and if the issue recurs, contact a heating engineer.

Evolve Combi Evolve System Error Codes:

E10 - Flame Lockout

Indicates a problem with flame detection or ignition.

E011 - Extraneous Flame

Detection of an unexpected flame.

E020 - Limit Thermostat

Issue with the limit thermostat.

E030 - Fan Fault

Problem detected with the fan.

E040, E041, E042 - Water Transducer Fault

Check system water pressure; indicates a transducer issue.

E060 - DHW Probe Fault

Issue with the domestic hot water probe.

4070 - Fault Flow Sensor Over Temperature

Indicates flow sensor issues or temperature differential alarm.

E077 - Main Zone Water Thermostat

Problem with the main zone water thermostat.

E080 - Return Line Probe Error

Issue with over temperature or differential alarm in the return line.

E090 - Flue Gases Over Temperature Probe

High temperature detected in flue gases.

E091 - Clean Primary Heat Exchanger

Indicates the need for cleaning the primary heat exchanger.

— - Water Pressure Low/High, Communication Lost

Indicate water pressure issues or loss of communication.

E021, E022, E023, E024, E067, E088, E097 - Iono Alarm

Potential ionisation issues.

E085, E094, E095 - Combustion Fault/High CO

Indicates combustion problems or high carbon monoxide levels.

E058 - Main Voltage Error

Issue with the main voltage supply.

E065 - Current Modulation Alarm

Problem with current modulation.

E086 - Obstruction Fumes Alarm

Alarm indicating obstruction in fumes exit path.

Additional Codes:

01 - Failure to Ignite

The boiler is unable to ignite.

02 - Overheat

The boiler is overheating.

03 - Fan/Flue Problem

Issue with the fan or flue system.

04 - Insufficient Water Pressure

Water pressure is too low.

05 - Reset as for Code 01

Advises reset similar to the failure to ignite.

06 - Hot Water Thermistor Open Circuit

Hot water thermistor has an open circuit.

07 - Primary Thermistor Open Circuit

Primary thermistor is open-circuited.

ADJ - Calibration

Indicates a need for calibration.

ACO - Service Operation

A service operation is in progress.

New Boiler Costs

Boilers can be a daunting purchase for many people as they’re an appliance with a lot of responsibility, providing heat for you and your family is something you want to get right. Boilers aren’t exactly a quickly disposable item either, potentially lasting you a decade.

Effectively, New boiler cost can be split into two segments: the first is the actual boiler itself (unit price), and the second is the cost of the boiler being installed (set up) in your property by an expert engineer. 

Here at iHeat, we want to remove all of this undue stress and make the decision making process of upgrading to a new central heating system, as easy as possible.

Boiler costs can vary depending on a number of factors including their brand, model, fuel, output, warranty, labour and installation type. Typically a new boiler will cost between £1,845 and £3,500, below is a list of average boiler installations offered by iHeat (guide only).

Installation Type

Price (inc VAT)

Combi to combi swap


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System to combi conversion


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New boiler install


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Back boiler to a combi


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System to system


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Frequently Asked Questions

How do you reset a Vokera boiler?

To reset a Vokera boiler, usually, one must locate the reset button on the boiler's control panel. Press and hold this button for a few seconds until the boiler powers off and restarts. The process can resolve temporary errors or malfunctions.

What are boiler fault codes?

Boiler fault codes are alphanumeric or colour-coded signals displayed by a boiler's control panel to indicate specific faults or issues. These codes help in diagnosing problems, facilitating quicker and more accurate repairs.

Why is my Vokera boiler flashing?

A Vokera boiler may flash to signal an operational fault. The pattern of the flashing light, often in sequence, corresponds to a fault code that can be referenced in the boiler's manual or by a professional to identify the underlying issue.

What does a red light mean on a Vokera boiler?

A continuous or flashing red light on a Vokera boiler generally indicates that the boiler is in lockout mode due to a fault. It's a safety feature that prevents the boiler from operating until the fault is addressed.

Why won't my Vokera boiler fire up?

If a Vokera boiler fails to ignite, it could be due to several issues, such as low water pressure, no gas supply, a faulty ignition, or a component within the boiler itself not functioning correctly.

Can I reset my boiler myself?

In many cases, homeowners can reset their boilers themselves by pressing the reset button. However, persistent problems after resetting indicate the need for professional assessment and repair.

How do I clear the error code on my boiler?

Clearing an error code typically involves rectifying the fault that caused it. After the problem is fixed, the error code on most boilers can usually be cleared by resetting the boiler. For persistent errors, consultation with a certified boiler engineer is advisable.

Stephen Day profile photo
Article by
Stephen Day | Co-founder
Gas Safe registered and FGAS certified engineer with over 20 years experience in the heating and cooling industry.