F73 Vaillant Boiler Fault Guide for Homeowners: Meaning, Symptoms, Actions, Costs, Causes & Prevention

The F73 Vaillant fault code indicates a problem with the pressure sensor. It may cause incorrect pressure readings. Watch for symptoms like unstable pressure or a failing boiler. There are no immediate safety issues. But, the fault can cause more problems if not fixed. The main causes include a malfunctioning pressure sensor or wiring issues. Regular maintenance can help prevent this fault from occurring. Always ensure a Gas-Safe engineer handles any repairs.

Meaning of the F73 Vaillant Boiler Fault

The F73 Vaillant fault code means a pressure sensor failure. It did not detect the correct system pressure. This fault usually occurs when the sensor reads an incorrect pressure. It may be too high or too low, even if the actual pressure is normal. The fault prevents the boiler from working efficiently. It needs accurate pressure readings to function properly.

The pressure sensor’s role is crucial for the safe and efficient operation of the boiler. It monitors the pressure within the system and sends this data to the boiler’s control unit. If the sensor fails, the boiler triggers the F73 fault to alert you. This fault often causes problems. The boiler may fail to ignite or shut down unexpectedly.

What causes the pressure sensor to fail?

Pressure sensor failure can occur due to several reasons. A build-up of debris or limescale in the sensor can cause this. It blocks the sensor’s ability to detect pressure accurately. Electrical issues, such as faulty wiring or loose connections, also lead to incorrect pressure readings. Additionally, wear and tear over time can cause the sensor to malfunction.

How does the F73 fault affect my boiler’s operation?

The F73 Vaillant fault prevents your boiler from reading the correct pressure. This is vital for safe and efficient operation. As a result, the boiler may fail to ignite or might shut down during operation. This fault may disrupt your heating system. You could lose heat or hot water.

Is the pressure sensor the only component involved in the F73 Vaillant fault?

The pressure sensor is the main cause of the F73 fault. Faulty wiring or connections to the sensor can also cause incorrect pressure readings. In some cases, the problem may lie with the control unit, which misinterprets the data from the sensor.

Can the F73 fault be a sign of other underlying issues?

Yes, the F73 fault can sometimes indicate other issues. These include a malfunctioning control unit or wiring problems. Sometimes, the fault may be due to a bigger issue in the heating system. For example, a leak or blockage may affect the pressure. It is essential to have a professional diagnose the root cause.

The next section will describe the symptoms of the F73 fault in more detail.

Symptoms of the F73 Vaillant Boiler Fault

The F73 Vaillant fault on your boiler presents several noticeable symptoms. You may see fluctuating pressure readings on the boiler’s display. The pressure may seem too high or too low despite normal conditions. Additionally, the boiler may fail to ignite, leaving you without heating or hot water. Another common symptom is the boiler shutting down unexpectedly. This often comes with an error message or a fault code.

These symptoms are direct indicators that the pressure sensor is not functioning correctly. If the boiler can’t maintain pressure, the pressure detection system is faulty. This inconsistency in pressure readings often causes the boiler to lock out as a safety precaution. It won’t operate until the issue is resolved.

How To Recognise The F73 Fault on Different Types of Vaillant Boilers

Vaillant Combi Boilers

On Vaillant Combi boilers, the digital screen shows the F73 fault. It also shows fluctuating pressure readings. You may notice that the boiler fails to start or shuts down during operation. The display might show inconsistent pressure levels, even if the system works. Sometimes, the boiler tries to ignite but shuts down soon after due to incorrect pressure readings.

Vaillant System Boilers

For Vaillant System boilers, the F73 fault is similar. The digital display shows the fault code and abnormal pressure readings. The boiler might not ignite at all, leaving you without heating or hot water. You might hear unusual noises from the boiler. It is trying to run with incorrect pressure readings. The pressure gauge may show an erratic needle. This indicates a malfunction in the pressure sensor.

Older Non-Digital Vaillant Boilers

Older, non-digital Vaillant boilers show the F73 fault differently. They lack a digital display for fault codes. In these models, the boiler may shut down or fail to ignite. There may be no visible error code. The boiler’s pressure gauge may show incorrect readings. It may read too high or too low, despite normal system pressure. These symptoms suggest the pressure sensor is faulty, despite no digital indication.

What to Do When Your Vaillant Boiler Shows the F73 Fault

First, turn the boiler off. Then, reset it using your user manual. This may temporarily resolve the issue if it is a minor glitch. If the fault persists, you should not attempt further repairs on your own. Contact a Gas-Safe registered engineer to inspect and repair the boiler. They have the skills and tools to fix the fault safely.

For safety, do not attempt to open the boiler casing or tamper with any internal components. Only do basic checks in the manual. For example, check that the boiler’s pressure is within the recommended range. If you suspect a gas leak or smell gas, shut off the gas and ventilate the area. Open windows and doors. Contact a Gas-Safe engineer immediately for further assistance.

How to Reset My Vaillant Boiler When the F73 Fault Appears?

To reset your Vaillant boiler, refer to the specific instructions in your user manual. This usually means pressing the reset button on the control panel and holding it for a few seconds. The boiler will attempt to restart, and the fault code may clear if the issue was temporary. If the fault reappears, do not reset the boiler. This could indicate a serious problem that needs a pro.

Should I Shut Off the Gas Supply If I See the F73 Fault?

You do not need to shut off the gas supply because of the F73 fault unless you smell gas or suspect a leak. If you smell gas, turn off the main gas valve. Ventilate the area and contact a Gas-Safe engineer. The F73 fault does not mean there is a gas leak.

Where Should I Check for Leaks When the F73 Fault Appears?

The F73 fault is mainly due to pressure sensor issues. However, visually inspect the boiler and area for any water leaks. Leaks can sometimes affect the pressure readings, contributing to the fault. If you see water pooling around the boiler or dripping from pipes, shut off the boiler and contact a Gas-Safe engineer. Do not attempt to fix leaks on your own.

Should I Continue Using My Boiler If the F73 Fault Clears After a Reset?

If the F73 fault clears after resetting the boiler, use it cautiously. Monitor it closely for any recurrence of the fault. If the fault reappears or the boiler acts up, stop using it. Look for unusual behaviour, like fluctuating pressure or shutdowns. Then, arrange for a professional inspection. Persisting in using a faulty boiler can lead to further damage or safety risks.

Cost to Repair F73 Vaillant Fault Code

The cost to repair the F73 fault on your Vaillant boiler varies. It depends on the specific issue and the parts needed. A simple repair, like resetting the boiler, costs at least £100. This cost covers the call-out fee for a Gas-Safe engineer and any minor fixes.

For complex repairs, like replacing the pressure sensor or fixing wiring, expect to pay £200 to £350. This cost includes the labour for the repair and the price of the replacement parts. The pressure sensor costs £50 to £100. The rest covers the engineer’s time and expertise.

If the fault is part of a larger issue, the repair cost may rise to around £500. This could be due to a faulty control unit or a more extensive wiring problem. This higher cost reflects the extra parts and labor needed to fix the issue. The maximum cost to repair an F73 fault is usually £500. This covers you for even the most complex cases.

In summary, F73 Vaillant fault repairs cost £100 to £500. It depends on the issue’s complexity.

We will detail the causes of the F73 fault. This will help you understand why it happens and how to fix it.

The 4 Major Causes of The F73 Vaillant Fault

The F73 fault on your Vaillant boiler is due to the pressure sensor or related parts. The main causes are: a bad pressure sensor, faulty wiring, debris or limescale, and control unit issues. Knowing these causes can help you spot problems. You can then take steps to fix them.

1. Malfunctioning Pressure Sensor

Your Vaillant boiler’s pressure sensor monitors the system’s pressure. It is critical to its function. A malfunctioning sensor is the most common cause of the F73 fault. Over time, the sensor may degrade. This could cause inaccurate readings of the boiler’s pressure levels. If the sensor fails to detect the correct pressure, the boiler triggers the F73 fault. This prevents further operation. This malfunction can be due to wear, moisture, or defects.

2. Faulty Wiring or Connections

Faulty wiring or loose connections can also lead to the F73 fault. The pressure sensor uses electrical connections to talk to the boiler’s control unit. If the wiring is damaged or loose, the sensor may send bad data or none at all. This disruption causes the boiler to display the F73 fault code. Wiring issues may result from poor installation, physical damage, or corrosion over time.

3. Debris or Limescale Build-Up

Debris or limescale in the boiler can block the pressure sensor. This prevents it from accurately detecting pressure levels. This build-up often occurs in areas with hard water. Debris or limescale can block the sensor. This causes inaccurate pressure readings, leading to the F73 fault. Regular maintenance and system flushing can prevent blockages.

4. Control Unit Issues

The control unit in your Vaillant boiler processes data from the pressure sensor. A faulty control unit may trigger the F73 fault. This can happen even if the pressure sensor is fine. The control unit can have issues due to software glitches, faults, or electrical problems. A professional must inspect the control unit to diagnose the fault.

Preventing Future F73 Faults

To prevent the F73 fault on your Vaillant boiler, maintain it regularly and care for it. The best way to avoid this is with annual boiler maintenance, ideally under a boiler cover contract.

During these annual checks, a Gas-Safe engineer will:

1. Inspect the pressure sensor.

2. Clean any debris or limescale.

3. Ensure all wiring and connections are secure.

Regular maintenance helps to identify and address potential problems before they lead to a fault.

Also, keep your boiler clean and dry. It will help the pressure sensor and other parts last longer. Monitoring your boiler’s pressure can help prevent the F73 fault. Report any unusual readings or behavior to a professional.

Disclaimer

Only a Gas-Safe registered engineer should do work beyond basic operation as described in the user manual. Repairing or servicing your boiler without the right qualifications can be dangerous. It may also void your warranty. Always consult a pro for any repairs or maintenance.