Vaillant F75 Fault Code - Error Code Explained & How to fix (Updated 2021)

The Vaillant F75 error is a fairly common fault code. When you see this fault code displayed on your Vaillant boiler it could be a number of potential causes. Continue reading...

Vaillant Fault	Meaning	Possible Causes
F75 F.75	Fault no pressure change	No Pressure: Sensor or pump failure, air in system (engineer required)

The F75 fault is typically the most popular vaillant failure and the fault is either something very simple as air in the system or a more problematic cause, such as a failed pump or sensor.

The ecoTEC boilers are renowned for reliability but when a pump fails (part no. 178983) we advice that our boiler engineers come and replace as this isn't something that can't be done as a DIY.

F75 Fault

A sensor blockage can cause a F75 fault which is caused either by the build-up of carbon deposits and debris in the filter system from the lack of boiler servicing or the system was not properly cleaned and treated when it was installed (cheap quotes tend to be the reason). The ecoTEC pressure sensor (Vaillant part no. 20059717) can become a problematic issue if you don't choose to have your boiler serviced every year.

Pump failures on the Vaillant ecoTEC boilers (Vaillant part no. 178983) are again caused by the lack of maintenance. These pumps are called Grundfos which are much more reliable than the Wilo pumps which had a high failure rate.

Fixing the Vaillant F75 fault

First of all before we start replacing sensors, pumps and wha-not we need to establish what fault is causing the F75. This can be achieved just by simply listening to the boiler, listen out to see if you can hear the pump run.

If you can hear the pump running, the pump is fine, you should hear it running for a few seconds every 20 seconds or so. If you can hear the pump, it is then highly likely that the pressure sensor causing the F75 fault code.

If you can't hear the pump then you can be fairly certain that this is where the fault lies and you will require our boiler engineers to replace the pump.