Facebook pixel
new boiler

Get a new boiler

Fixed price boilers, next day

See boiler prices
new air conditioning

Air Conditioning

Get a quote
new heat pump

Heat Pumps

Coming soon

new ev charger

EV Chargers

Get a quote
boiler servicing

Boiler Servicing

Get a quote

Last updated: 11th February, 2024


Viessmann F2 Fault

Viessmann F2 Fault

Key takeaways

  • The F2 fault code indicates a burner lockout in Viessmann boilers.
  • It is generally advised to consult a Gas Safe registered engineer when dealing with an F2 fault.
  • The cost of fixing the issue depends on the complexity of the underlying problem.

Error codes are integral to the effective operation and maintenance of modern boilers. They serve as a vital diagnostic tool for identifying issues within the system.

Encountering an F2 fault code on a Viessmann boiler can be both inconvenient and concerning for homeowners. This error code signifies a burner lockout, an issue rendering the burner inoperative and thus preventing the unit from heating water. 

The fault stems from several potential causes, from simple problems like a lack of gas supply to more complex issues such as electronic component failures. It is essential to understand what an error code indicates to take the appropriate steps toward resolution.

The burner lockout suggested by the F2 fault code means that the safety parameters within the boiler have detected an abnormality that could pose a risk, prompting the system to shut down the burner. While some troubleshooting steps can be carried out by the homeowner, such as checking for obvious obstructions or resetting the boiler, it's often necessary to seek expertise from a qualified engineer. 

Ascertaining the cause and fixing an F2 fault may vary in complexity and cost, depending on the specific underlying issue, and in some cases, it may highlight the need for a more substantial boiler repair or even replacement.

What Is a Boiler Error Code?

Error codes are integral to the effective operation and maintenance of modern boilers. They serve as a vital diagnostic tool for identifying issues within the system.

Explain What Boiler Error Codes Are in General

Error codes on boilers are alphanumeric or numeric codes that appear on the control panel of the unit. These codes correspond to specific problems that the unit has detected. For instance, a code may signify a fault with the ignition system, while another may indicate a problem with the water pressure. With fault codes, the boiler essentially communicates to users and engineers what is wrong, or could potentially be starting to go wrong, inside the unit.

Manufacturers provide a key to these codes, typically in the user manual or on their website, explaining what each code means. Through regular maintenance, homeowners and engineers can use the codes to perform a diagnosis before more severe problems arise.

Importance of Understanding Error Codes for Boiler Maintenance

Understanding the fault codes is pivotal for maintaining the longevity and efficiency of a boiler. When a code appears, it can signal that the boiler requires immediate attention, which if ignored, could lead to more extensive damage or even a complete breakdown.

Interpreting these error codes promptly:

  • Helps in ensuring that the boiler operates safely and efficiently

  • Reduces the risk of unexpected failures that can be costly and inconvenient

  • Maintains the validity of the warranty, which can be voided if the boiler's issues are not addressed in a timely fashion

  • Requires the expertise of a certified Gas Safe registered engineer for complex issues, safeguarding against the risks associated with incorrect handling

Regular maintenance, facilitated by understanding these codes, allows for early detection of potential problems and can prevent the need for more significant repairs in the future.

What Does the Viessmann F2 Fault Mean?

Encountering an F2 fault code on a Viessmann boiler signals a notable malfunction within the system. It points toward the shutdown of the burner, which directly impacts heat production and hot water supply.

Detailed Description of the Specific Error Code

The F2 error code appearing on a Viessmann boiler indicates a burner lockout, a safety feature designed to prevent any damage to the boiler should a fault arise. This lockout stops the burner from igniting, meaning that the essential production of heat and subsequent hot water provision is halted.

Possible Reasons Why This Error Code Appears

Multiple factors can trigger the appearance of an F2 fault code on a Viessmann boiler. Common culprits include:

  • Blockages: These can be due to heating sludge, dirt, rust, or limescale accumulating within the system.

  • Airlocks: Specifically pump airlocks, which impede the normal flow of water within the heating system.

  • Ventilation Issues: Poor ventilation or a blocked flue may result in inadequate air supply for combustion.

  • Pump Issues: A pump that has been incorrectly installed or is malfunctioning can prevent proper circulation throughout the system.

  • Extreme Weather Conditions: A frozen condensate pipe can lead to system failure.

  • System Degradation: Over time, debris and components wear can cause faults such as flame loss or overheating, resulting in the F2 fault code display.

The diagnosis of an F2 error requires careful consideration of these potential issues, and typically, a trained professional should be consulted to address the fault effectively.

Signs of the Viessmann F2 Fault

Understanding the signals of a Viessmann F2 fault is paramount for maintaining an efficient heating system. Homeowners may notice distinct symptoms that signify this specific error is affecting their boiler's performance.

List and Explain Common Signs and Symptoms That Indicate This Specific Error

  • Strange noises: When the boiler is in operation, listen for unusual sounds, such as grinding or humming. These noises may suggest issues with the internal components, like the pump.

  • Reduced hot water pressure: Should the water flow from taps become weaker, it could point to the F2 error. Insufficient hot water pressure indicates a problem within the heating system affecting its normal function.

  • Radiators not heating evenly: If some radiators are cold while others are hot, or if they take longer to heat up, this indicates an inconsistency in circulation that can be attributed to the F2 fault.

  • Fluctuating boiler pressure: Watch the pressure gauge; if the needle is erratic, it reveals a disturbance in pressure stability, often associated with the F2 fault code.

  • Temperature irregularities: An error in temperature regulation or circulation within the system can trigger the F2 code. These discrepancies in heating can range from no hot water production to inadequate heating performance.

Identifying these signs early can help prevent a full boiler lockout, maintaining continuous and efficient heating and hot water supply. Regular servicing is recommended to keep the boiler in optimal condition and to troubleshoot these symptoms effectively.

Can I Fix This Boiler Error Code Myself?

When faced with a Viessmann boiler presenting the F2 fault code, homeowners may wonder if they can address the error themselves. This section outlines practical DIY steps and advises when it's safer to consult a professional.

DIY Tips for Resolving the Error

Reset Procedure: The first recourse should typically be to attempt a boiler reset. Locate and press the reset button—often found beneath the boiler's cover plate—and wait for the system to cycle and attempt re-ignition.

  • Inspection of Wiring: If the reset doesn't resolve the issue, a visual check of the boiler's wiring with a multimeter can determine electrical continuity. This requires a basic understanding of electrical systems to perform safely.

  • Repressurising the Boiler: An F2 error can also indicate low system pressure, necessitating repressurisation. The boiler's manual should provide guidance on adjusting the pressure via the filling loop.

  • Thawing Frozen Pipes: In colder weather, condensate pipes might freeze, tripping the F2 fault code. Gentle thawing with warm, not hot, cloths can rectify this. Insulating pipes can prevent future occurrences.

Warning: While DIY inspections and minor adjustments can be performed by homeowners, detailed interventions should not be attempted. Opening the boiler or tampering with its internal components is risky and illegal if not Gas Safe certified.

Warnings or Advice on When to Avoid DIY and Seek Professional Help

  • If the issue persists after a reset or repressurisation, this might suggest deeper mechanical or electrical issues, for which professional help is recommended.

  • When Not to DIY: If at any point a gas leak is suspected, it's imperative to cease all attempts at DIY and evacuate the premises. Once safe, contact a Gas Safe registered engineer.

  • The complexity of boiler systems requires expertise; hence, a certified Gas Safe registered heating engineer should address faults related to the burner, gas supply, or internal components.

In summary, while initial troubleshooting steps are within the homeowner's purview, for safety, legality, and warranty considerations, more complex issues necessitate a boiler engineer's expertise.

Do I Need to Contact a Gas Safe Engineer to Fix This Error Code?

Experiencing an F2 fault code on a Viessmann boiler suggests a burner malfunction. It's imperative for safety and technical reasons to assess whether professional intervention is needed.

Advice on When It's Necessary to Call a Professional

Safety concerns: If one encounters the F2 error code, it is pivotal to consider the functionality of the burner, which has ceased to operate effectively. This malfunction could pose a risk due to gas and combustion-related hazards.

  • Lack of heating or hot water: Should the boiler's failure prevent the provision of heating or hot water, this escalates the urgency for professional help.

  • Technical expertise: A qualified engineer is equipped to diagnose and mend the fault, ensuring the safe and efficient operation of the boiler.

Users with technical knowledge may conduct preliminary checks, such as verifying the boiler's pressure or ensuring it has electric power. However, in the absence of a clear and simple solution, seeking a certified Gas Safe engineer is highly advised.

Explanation of What a Gas Safe Engineer Is and Why Their Expertise Is Important

Certification explained: A Gas Safe engineer is a technician who has been authoritatively certified to work on gas appliances safely and competently. In the UK, the Gas Safe Register is the official body designated by the relevant Health and Safety Authority.

  • Essential qualifications: To become Gas Safe registered, engineers must evidence their proficiency through assessments. Only those listed on the Gas Safe Register are legally allowed to work on gas equipment.

  • Importance of expertise: Utilising a Gas Safe engineer's expertise ensures compliance with safety standards and can circumvent the potential for gas leaks, carbon monoxide poisoning, or other serious safety risks.

Therefore, when confronted with an F2 error code, enlisting a Gas Safe engineer is not only a wise decision but a necessary action for one’s safety and the boiler’s longevity.

How Much Does Fixing the Viessmann F2 Fault Cost?

The cost of addressing a Viessmann F2 fault can vary. Key financial considerations include the need for replacement parts or a perhaps a professional boiler service, and also whether the boiler is still under warranty coverage.

General Cost Range for Fixing This Error

Costs for repairing a Viessmann F2 fault in a boiler can typically range from £45 to £200 if doing an annual boiler servicing and minor repairs. This may scale up to over £500 if significant parts or a replacement boiler are needed, especially considering the central heating system's complexity.

  • Minor repairs: £45 - £100

  • Annual boiler servicing: £80 - £160

  • Major repairs / Parts replacement: £150 - £500+

  • Replacement boiler: £1,500 - £3,000+

Factors That Might Affect the Cost

Several factors influence the final bill:

  • Warranty coverage: Whether the repair costs are partially or fully covered under the boiler's existing warranty.

  • Central heating system: Complexity and compatibility of the boiler with the existing heating system.

  • Boiler age and model: Older or discontinued models may cost more due to the difficulty in sourcing parts.

  • Efficiency: More efficient fixes may cost more initially but could be more cost-effective in the long run.

  • Plumbing requirements: More extensive plumbing work increases the cost.

The necessity of professional intervention cannot be overstated; only certified technicians should conduct boiler repairs to maintain safety and efficiency. It's crucial for homeowners to consider these factors and potentially invest in annual boiler servicing to preempt such faults.

Do I Need A New Boiler?

When a Viessmann boiler displays the F2 fault code, homeowners may wonder if repairs will suffice or if a new boiler is necessary. This section aims to provide clarity on this matter.

Do I Need a New Boiler? Criteria to decide whether a repair is sufficient or if a new boiler is required.

Homeowners should evaluate several factors before deciding on boiler replacement. These include the age of the boiler, frequency of breakdowns, the cost of repairs versus a new boiler, and efficiency ratings. If the boiler is relatively new and the F2 fault is an isolated incident, a repair is often the most cost-effective solution. However, persistent issues or a boiler nearing the end of its typical lifespan could warrant a replacement.

Information on the lifespan of boilers and when replacement is typically recommended.

On average, boilers have a lifespan of 10-15 years. Factors influencing this duration include the make, model, usage patterns, and how well it has been maintained. A well-serviced boiler can outlast this estimate; however, as a boiler ages, it becomes less efficient and more prone to breakdowns. Manufacturers often provide guidelines on service life, suggesting when homeowners should consider replacement.

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


Get a quote

System to combi conversion


Get a quote

New boiler install


Get a quote

Back boiler to a combi


Get a quote

System to system


Get a quote


The Viessmann F2 fault code signals a variety of issues that can afflict a boiler system. Primarily, it indicates a problem with the central heating pump or the presence of blockages in the system. These challenges are manageable through professional intervention.

Common causes for the F2 fault include:

  • Pump Failure: Often stemming from inadequate maintenance, the degradation of the pump requires immediate attention.

  • Blockages: Accumulated debris or sludge can hinder the water flow, exerting unnecessary strain on the heating system.

  • Burner Lockout: This condition prevents the burner from producing the essential flame required for heating.

To remedy these malfunctions, homeowners are advised to seek a Gas Safe registered engineer's expertise. Regular boiler servicing emerges as a crucial preventive measure against future breakdowns. Solutions, like a system power flush, can eliminate the disruptive sludge build-up, ensuring a seamless operation.

In instances where the boiler's burner has locked out, identifying the root cause – whether it's a lack of maintenance or a component failure – will govern the precise approach necessary for rectification. Ultimately, addressing the manifestations of the F2 fault code promptly can limit the downtime of the heating system and curb the risk of more severe damage.

Get a quote

Frequently Asked Questions

What is the F2 error on a boiler?

The F2 error on a Viessmann boiler indicates a problem with the burner, leading to a boiler lockout. This is often a safeguard against potential damage to the system.

How do you clear the fault on a Viessmann boiler?

To clear an F2 fault on a Viessmann boiler, one should consult the user manual for specific reset procedures, which typically involve turning the boiler off and on again.

How do you reset the pressure on a Viessmann boiler?

Pressure reset on a Viessmann boiler usually requires checking the pressure gauge and adjusting the filling loop to correct the water pressure.

Why is my boiler's F2 fault reset not resolving the issue?

If the F2 fault reset does not remedy the problem, it may indicate a persistent issue with the burner or other components necessitating professional assistance.

What is the F2 error code on a Viessmann combi?

On a Viessmann combi boiler, the F2 error code suggests a circulation fault, possibly due to a broken pump or airlock within the system.

What does F2 mean on a Viessmann boiler?

F2 means the boiler has detected a fault within the burner function or temperature control, prompting a shutdown to prevent damage.

Why does my Viessmann boiler keep losing pressure?

A Viessmann boiler losing pressure could be due to a variety of reasons, such as leaks in the system, a failing pressure relief valve, or an issue with the expansion vessel.

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.