The Vaillant F75 Fault Code: Meaning and Solution

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The Vaillant F75 Fault Code: Meaning and Solution

The Vaillant F75 Fault Code: Meaning and Solution

The Vaillant F75 Fault Code: Meaning and Solution

Are you encountering the F75 error code on your Vaillant boiler? In this article, we will provide you with an explanation of this common fault code and how you can fix it.

Before you start, it is essential to determine the cause of the fault code rather than simply restarting the boiler. Ignoring the error code and restarting the boiler may not address the root of the problem and may even put your boiler and property at risk. Only a registered Gas Safe engineer should open the boiler casing.

The F75 error code is displayed on specific Vaillant boiler models and may be caused by various factors. To protect the boiler and ensure safety, the boiler may "lock out" and display the F75 error code.

If your boiler is old and unreliable, causing costly repairs, consider answering a few questions to get a fixed price for a new installation.

Steps to Fix the F75 Error Code It is not recommended to tamper with the boiler yourself. A Gas Safe engineer should handle any necessary repairs. The engineer will diagnose the issue and make any necessary repairs to get your boiler back up and running.


Vaillant EcoTec

Vaillant EcoTec Plus

Vaillant EcoPro


The Vaillant F75 Error Code: Explanation and Causes

The F75 error code is displayed when the boiler experiences pressure problems and "locks out", showing the F75 code on the user interface. The error can be caused by multiple faults and the diagnostic process may be complex. However, two common causes are a defective water pressure sensor and pump or too little water in the appliance.

A faulty pressure sensor can result in the F75 error code. In early models of the Vaillant EcoTec range (2005-2010), the pressure sensor was known to experience issues more frequently. However, improvements have been made in newer models and this issue is not as common.

If you have a newer EcoTec pro and don't suspect it's related to the manufacturing fault in older versions, a faulty pressure sensor can be caused by the buildup of debris such as rust, sludge, and limescale deposits. A complete system cleanse, such as a power flush, can help prevent this issue.


The Vaillant F75 error code is displayed when the boiler is having a pressure issue, causing it to shut down or "lock out" and display the F75 code. The code means that no sudden change in pressure was detected when the pump was turned on. This error can be caused by multiple malfunctions and diagnosing the root of the problem can be complex. Two common reasons for this fault are a defective water pressure sensor or pump and insufficient water in the appliance.

An old and unreliable pressure sensor, particularly in early versions of the Vaillant EcoTec range, can cause the F75 error code. However, improvements have been made to newer models, and other causes of a faulty pressure sensor include debris buildup from rust, sludge, and limescale deposits. In many modern boilers, including Vaillant boilers, a Grundfos boiler pump is used, which is known for its reliability. However, older Vaillant boilers used a less reputable Wilo pump that has a history of failing prematurely.

The Vaillant models most prone to the F75 fault code are the EcoTEC Plus and the EcoPro 28. To diagnose a faulty boiler pump, you can reset the boiler by pressing the reset button with the flame icon. If the issue persists, it is recommended to consult a registered Gas Safe engineer.



Diagnosing and Fixing the Vaillant F75 Error Code

The Vaillant F75 error code is a common issue in older EcoTEC Plus and EcoPro 28 boilers that use a Wilo pump. If your Vaillant boiler is showing this code, it's likely due to a faulty boiler pump or pressure sensor. Here's how to diagnose and fix the problem:

Diagnosing a Faulty Boiler Pump:

  1. Press the reset button on your boiler, which has a flame icon embossed on it.
  2. Turn on a hot tap near the boiler and let the heat pump start.
  3. Listen for the pump's operation, which should produce an audible humming sound and gentle vibration.
  4. If you don't hear or feel anything, the pump is likely broken and in need of repair.
  5. If the pump operates normally but goes silent and you lose hot water, the F75 error is probably due to a broken pressure sensor.

Diagnosing a Faulty Pressure Sensor: If the pump is operating normally but you still get the F75 error code and lose hot water, the cause is probably a faulty pressure sensor. These sensors can become clogged with debris and dirt, blocking the necessary signals and causing the pump to not trigger. Cleaning the sensor is not recommended due to high labor costs, so it's best to replace it with a new one.

Fixing the F75 Error: Unfortunately, there is no DIY solution for the F75 error. A broken pump needs to be replaced by a registered Gas Safe engineer, and the same goes for a faulty pressure sensor. Replacing the sensor is usually the better option due to low cost compared to high labor costs for cleaning it.

We have guides available for many other common Vaillant boiler error codes, including the F29 and F62 codes.


Vaillant F22 Error Code.

Vaillant F23 Error Code.

Vaillant F24 Error Code.

Vaillant F25 Error Code.

Vaillant F27 Error Code.

Vaillant F28 Error Code.

Vaillant F29 Error Code.

Vaillant F54 Error Code.

Vaillant F62 Error Code.

Vaillant F72 Error Code.

Vaillant F75 Error Code.

Vaillant F76 Error Code.

Vaillant F83 Error Code.


The Cost of Repairing an F75 Error If your boiler is showing the F75 error, it could be due to a faulty pump or pressure sensor, which will require the attention of a registered Gas Safe engineer. The cost of repairing the error can vary depending on your boiler model. Complex boilers with more intricate systems will require more time and effort to repair, resulting in higher costs.

Price of a New Boiler Pump The cost of a new boiler pump, not including installation, from a reputable brand is typically between £200 and £300.

Cost of a Replacement Pressure Sensor A new pressure sensor, excluding labor, can cost between £150 and £250.

Preventing the F75 Error To avoid the F75 error, it is recommended to have your boiler serviced annually, as outlined by most boiler manufacturers. During the service, the Gas Safe engineer will inspect the system for any issues and perform routine maintenance, including cleaning to prevent blockages in the pressure sensor. A routine power flush is also recommended to keep your heating system free from dirt and sludge, which can cause blockages and corrosion in your boiler and heating system.

If your boiler is old and no longer under warranty, it may be time to consider a replacement before it causes more costly repairs.


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