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Last updated: 2nd November, 2023


Vaillant F73 Error Code - How To Fix

Vaillant F73 Error Code - How To Fix

Key takeaways

  • The F73 error code is linked to issues with the water pressure sensor in Vaillant boilers.
  • Common causes include faulty pressure sensor, loose or damaged connections, and water damage to the wiring.
  • Basic troubleshooting can often resolve the issue, but professional help may be needed if the problem persists.

The Vaillant F73 error code indicates a problem with the water pressure sensor, which can lead to a loss of heating and hot water.

Vaillant boilers are known for their efficiency and reliability, making them a popular choice for many homeowners. But like any home appliance, they can sometimes experience issues, and one such problem is the F73 error code. 

This error can cause concern and inconvenience, but it's important to understand what it means and how to fix it.

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The Vaillant F73 error code typically occurs when there is an issue with the boiler's water pressure sensor, which is responsible for detecting the water pressure within the system. Common causes for this error include a faulty pressure sensor, loose or damaged connections, or water damage affecting the wiring. 

If left unaddressed, the F73 error can lead to further complications and impact the overall performance of your Vaillant boiler.

Knowing how to identify and resolve the Vaillant F73 error code can save you time and money, as well as ensuring that your boiler continues to operate safely and efficiently. Fortunately, most instances of the F73 error can be resolved with some basic troubleshooting, but it's essential to know when to call in a professional if the problem persists.

Key Takeaways

  • The F73 error code is linked to issues with the water pressure sensor in Vaillant boilers.

  • Common causes include faulty pressure sensor, loose or damaged connections, and water damage to the wiring.

  • Basic troubleshooting can often resolve the issue, but professional help may be needed if the problem persists.

Understanding Vaillant F73 Error Code

The Vaillant F73 error code is a common issue that can affect various models of Vaillant boilers, such as the ecoTEC Plus, aquaTEC, and ecoMAX. This fault code indicates a problem with the water pressure sensor, which may result in the boiler operating inefficiently or not functioning at all.

One potential cause of the F73 error code is a faulty pressure sensor. This sensor is responsible for monitoring the boiler's water pressure. If it malfunctions, the boiler may not be able to regulate its operation correctly. Sometimes, removing and cleaning the sensor can resolve the issue, though replacing the sensor might be necessary if the problem persists.

Another possible reason for the F73 error is a disconnection between the pressure sensor and the printed circuit board (PCB). The PCB controls various functions within the boiler, so a lack of communication between the pressure sensor and the PCB can result in the F73 fault code. Ensuring that the connector and wiring are correctly attached can help resolve this problem.

Water damage to the wiring is another common cause of the F73 fault code. Internal boiler leaks can result in water seeping into the wiring, causing damage and interfering with the sensor's readings. Typical culprits for such leaks are broken heat exchangers or pumps with damaged seals. Diagnosing and repairing these issues is essential to prevent further water damage and resolve the F73 error.

When attempting to fix the F73 fault code, it is crucial to follow safety precautions and consult your boiler's user manual or a professional technician if you are unsure about the process. Additionally, regular boiler maintenance and inspections can help prevent such issues in the future and prolong the lifespan of your Vaillant boiler.

Common Causes of Vaillant F73 Error

Low Water Pressure

Erroneous low water pressure in the boiler is a common source of the F73 error code. When the pressure falls below the necessary level, it may trigger this fault code, disrupting the boiler's operation. If you're experiencing this issue, examine the pressure gauge and ensure it's in the right range. Adjusting the filling loop or seeking professional assistance might help resolve this problem.

A problem with faulty wiring can lead to pcb issues causing a lower water pressure meaning the vaillant eco tec boiler could show a f73 error code on the system meaning a new boiler 

Faulty Wiring

Faulty wiring within the boiler could be responsible for the F73 error code. Water damaged wiring, in particular, is a frequent culprit, often resulting from internal leaks. Reliable connections are paramount, as loose or corroded connections can lead to incorrect readings and subsequent F73 fault code display. Inspect the boiler's wiring harness for potential damage. If you discover damaged wiring, arrange for a qualified technician to replace it.

Faulty Pressure Sensors

A faulty pressure sensor might induce the F73 error code. These sensors play a pivotal role in monitoring various aspects of the boiler's functionality—including pressure, gas flow, and water pressure—ensuring seamless operation. Faults within the pressure sensor can result in a failure of the water pressure sensor signal, triggering the F73 error code. Replacing the faulty pressure sensor might be necessary to fix the issue.

Water Leaks

Water leaks within the boiler might contribute to the F73 error code in several ways. For instance, leaks from heat exchangers or pumps with damaged seals can cause water-damaged wiring. These leaks can result in incorrect readings, leading to the F73 error code display. Furthermore, leaks might impact the boiler's water pressure. In such cases, it's essential to identify the source of the leaks and address them accordingly. Professional assistance is often advisable to ensure proper remediation and prevent further damage.

Impact of F73 Error on Your Vaillant Boiler

The F73 error on a Vaillant boiler can significantly affect its performance and efficiency. This error code is specifically related to the water pressure sensor in the boiler, which is responsible for maintaining the correct pressure levels in the system. When the F73 error occurs, it compromises the overall operation of your boiler, leading to potential issues related to gas flow, temperature regulation, and the functioning of radiators.

One primary effect of the F73 error is its impact on temperature control. When the water pressure sensor malfunctions or gets disconnected, your boiler may struggle to maintain the desired water temperature. Consequently, radiators linked to your boiler may feel cooler or fail to heat up consistently, leaving you with a cold and uncomfortable home environment.

Another crucial aspect is the gas flow regulation. With a faulty F73, the boiler might not efficiently regulate the gas flow, causing inefficiency in fuel consumption and an increase in energy bills. Additionally, an improper gas flow can lead to incomplete combustion, which may damage the heat exchanger and other internal components of the boiler over time.

Safety is paramount in the event of an F73 error, as a malfunctioning pressure sensor can cause the boiler to lockout. This means the boiler will cease operation to prevent potential damage to itself or the surrounding environment. In some cases, this error may stem from a boiler leak, which can cause corrosion on wiring harnesses or damage to the printed circuit board.

Addressing the F73 error is essential to preserve the longevity of your boiler. To rectify the issue, a Gas Safe Registered engineer may need to replace the faulty pressure sensor, reconnect wiring, or even install a new boiler. On some Vaillant boiler models, such as the ecoTEC Plus or the Vaillant ecoTEC, the F73 error may also lead to issues with the NTC (Negative Temperature Coefficient) thermistor – a component responsible for accurate temperature readings.

In summary, the F73 error on your Vaillant boiler can influence various aspects of its functioning, ranging from temperature control to gas flow regulation and safety measures. Swiftly addressing this error can help preserve the performance, efficiency, and lifespan of your boiler, keeping your home warm and comfortable throughout the year.

Steps to Resolve Vaillant F73 Error

In this section, we will discuss several methods to resolve the Vaillant F73 error code. This code is related to a faulty water sensor, wiring issues, or a defective printed circuit board. By following these steps, we can identify and potentially fix the problem with your boiler.

Resetting the Boiler

Firstly, try to reset the boiler. Doing so can often resolve minor faults and intermittent issues. Turn off the power, wait for a few minutes, then turn it back on. Check if the F73 error code has cleared. If the problem persists, proceed to the next step.

Bleeding the Boiler

Bleeding the boiler can help alleviate pressure issues within the system, as it removes any trapped air. To bleed the boiler, you will need a radiator key or a flathead screwdriver. Ensure the heating is off, and open the bleed valve one radiator at a time, starting with the lowest one. Release the air until water begins to flow out, then close the valve. Repeat this process for all the radiators in your home.

Checking For Leaks

Look for any signs of water leakage in and around the boiler. Leaks can result from corroded connections or faulty seals, leading to wiring damage and the F73 error code. If you discover a leak, it is advisable to call a Gas Safe registered engineer to fix the problem.

Repairing or Replacing Faulty Parts

Inspect the wiring harness, sensor, and PCB for any visible damage. If you find any faulty parts, these may be the cause of the F73 error code:

  • Faulty Pressure Sensor: A defective pressure sensor can lead to inaccurate readings, triggering the F73 error code. Replacing the sensor may resolve the issue.

  • Wiring Harness: If connections on the wiring harness appear corroded or damaged, it may be necessary to replace the entire harness.

  • Circuit Board: In some cases, a faulty printed circuit board (PCB) could be responsible for the F73 error. A Gas Safe registered engineer is recommended for PCB repairs or replacements.

In conclusion, resolving the Vaillant F73 error code may involve resetting the boiler, bleeding the system, checking for leaks, or repairing or replacing faulty components. It is always advisable to consult a Gas Safe registered engineer if you are uncertain about carrying out repairs yourself. Remember, safety first.

When to Contact a Professional

It's essential to know when it's time to call a professional, particularly when dealing with a Vaillant F73 error code. While some boiler issues can be resolved with simple troubleshooting techniques, others necessitate the expertise of a Gas Safe registered engineer.

The F73 fault code indicates a problem with the low water pressure sensor in your Vaillant boiler. In most cases, this issue cannot be fixed by an end user. Attempting to repair a boiler without proper knowledge and certification can be dangerous and may even be illegal, as it involves working with gas supply. Hence, when an F73 error code is displayed, it is advisable to contact an engineer immediately.

A Gas Safe registered engineer has the necessary skills and experience to diagnose and repair the fault. They can identify the root cause, whether it's a loose sensor connection, water-damaged wiring, or a faulty sensor, and provide the appropriate solution. Unregistered individuals are not qualified to work on gas appliances, so always verify the engineer's Gas Safe credentials.

When you contact a professional heating engineer, they will likely ask for information about the fault code to prepare an accurate quote for repairing the issue. Be prepared to give details such as the boiler model, age, and any other fault codes that may have appeared. This will help streamline the process and expedite the repair, ensuring your boiler is back up and running efficiently.

In summary, when dealing with an F73 error code on your Vaillant boiler, it's crucial to seek the assistance of a qualified professional. By hiring a Gas Safe registered engineer, you can be confident that the necessary repairs will be carried out safely and correctly.

Safety Precautions While Handling Vaillant F73 Error Code

When dealing with a Vaillant F73 error code, it is essential to take several safety precautions to ensure that your boiler and property remain protected. First and foremost, always enlist the help of a Gas Safe registered engineer to assess and repair the issue. Working with gas appliances can be hazardous, and their expertise guarantees the safe resolution of the problem.

One reason for the F73 error code involves loose connections or water-damaged wiring. These issues can pose a risk to the user and the boiler, so it is essential to avoid attempting DIY repairs. Leave it to a qualified professional as tampering with the wiring can be dangerous and might inadvertently lead to more complications.

The lockout feature plays a critical role in safeguarding both your property and the boiler’s internal components. A heating system in use generates pressure, which can exacerbate a leak and create more property damage. The lockout prevents the boiler from continuously operating under these conditions, mitigating the risk of further damage.

In conclusion, always adhere to the following safety precautions while handling a Vaillant F73 error code:

  1. Engage a Gas Safe registered engineer to assess and fix the issue

  2. Avoid tampering with the wiring as it can be dangerous and lead to more complications

  3. Be mindful of the lockout feature protecting your property and boiler

By following these guidelines, you can ensure the safe and efficient resolution of the Vaillant F73 error code.

Additional Troubleshooting Tips for Vaillant F73 Error Code

The F73 error code on Vaillant boilers is typically due to a fault with the water pressure sensor. This can be caused by a variety of issues, such as faulty components, disconnected wiring, or leaks. To help resolve the F73 error code, the following troubleshooting tips can be useful.

Firstly, check the boiler's pressure gauge. If the water pressure appears low, try increasing it by opening the filling loop slowly. This action should bring the system back to the optimal pressure level (usually around 1.5 bar). Don't forget to close the filling loop after adjusting the pressure!

Next, inspect the wiring harness and its connections. Look for signs of corrosion or damage, as this may be affecting the ability of the sensor to communicate with the rest of the system. If any issues are found, it is advisable to call a qualified Gas Safe engineer to repair or replace the damaged components.

Furthermore, examine the pressure sensor itself and the printed circuit board (PCB). If the sensor is covered in debris or if the PCB shows signs of damage, this could be contributing to the F73 error code. Cleaning the pressure sensor and assessing the PCB for damage are essential steps in troubleshooting the issue.

Consider checking the heat exchanger, radiators, and seals for any water leaks. A leaking pressure sensor or other components can cause corrosion on the connections, which may ultimately lead to the F73 error. Identifying and repairing the source of the leak should help resolve the issue.

Lastly, it's worth checking the gas supply and gas valve. While these components are not directly related to the water pressure sensor fault, they contribute to the overall efficiency of the boiler and may influence other related factors such as water temperature and circulation. Ensuring a steady gas flow and a functioning gas valve is essential for the optimal operation of the boiler.

Bear in mind, while some of these checks can be performed by the homeowner, it is always recommended to obtain the services of a professional Gas Safe engineer when tackling issues with a boiler, as they possess the training, experience, and safety knowledge to diagnose and repair these systems effectively.

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Frequently Asked Questions

What does F73 mean on Vaillant boiler?

F73 error code on Vaillant boilers indicates an issue with the water pressure sensor. This may affect ecoTEC Plus, aquaTEC, and ecoMAX models. The error code suggests that the low water pressure sensor is not operating correctly.

What does F 73 mean on a boiler?

On a boiler, the F73 fault code signifies a problem with the water pressure sensor. This sensor is essential for maintaining safe and efficient operation of the boiler. Faults can be caused by a faulty sensor, loose connections, or water-damaged wiring.

What is the F 83 fault on a Vaillant NTC temperature gradient?

F83 fault code on Vaillant boilers is related to the Negative Temperature Coefficient (NTC) temperature gradient. This error indicates that there is an inconsistency between the temperature readings from the flow and return NTC sensors. This issue might result from a malfunction in one of the NTC sensors, a problem with the wiring, or faulty connections.

What is fault 83 on the boiler?

Fault code 83 on a boiler refers to an error in the NTC temperature gradient readings, indicating an inconsistency between the temperatures measured at the flow and return NTC sensors. This can be caused by faulty sensors, wiring issues, or poor connections.

How do you clear a fault on a Vaillant boiler?

To clear a fault on a Vaillant boiler, you need to reset the boiler following the steps below:

  • Turn off the boiler using the controls or switch.
  • Wait for a few seconds.
  • Turn the boiler back on.
If the fault persists, you may need to consult a professional engineer to diagnose and fix the issue.

Should I turn my boiler off if it has a fault code?

It's generally advisable to turn off a boiler displaying a fault code. Continuing to operate the boiler with a fault code may lead to further damage or even unsafe conditions. Turning the boiler off and resetting it might help to clear the fault. However, if the problem persists, it is best to seek professional advice or assistance.

Will it damage my boiler if I turn it off?

No, turning off your boiler will not damage it. In fact, it can be a good idea to turn off the boiler when it is showing a fault code, as this may help to protect it from further damage while the fault is being resolved. Remember to consult a professional engineer if the fault persists, even after turning the boiler off and resetting it.

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