If you have a Vaillant ecoTEC boiler, one of the most common fault codes that you’re likely to see is a Vaillant F75 error code. Unfortunately, this is also one of the more frustrating error codes since it has several possible causes and a variety of remedies that may be needed to get your boiler up and running again.

The official explanation of the Vaillant error F75 is that no pressure change can be detected when the pump starts up. This means that, when the pump is functioning, the boiler cannot detect the pressure that it should. In general, this means there is something wrong with either the pressure sensor or the pump itself. A Gas Safe engineer is the best person to offer help in this regard, since they are trained and experienced in dealing with Vaillant fault codes.

What Are The Common Causes Of A Vaillant F75 Fault Code?

The original Vaillant ecoTEC boilers featured a pump that was manufactured by a company known as Wilo. However, it is now known that those pumps have an especially high rate of failure. They are especially known to be likely to split and leak. More modern ecoTEC boilers feature a pump made by a company known as Grundfos. These pumps are long-lasting and more durable than those made by Wilo, and have a lower rate of failure. Therefore, if you have an older ecoTEC boiler, it’s likely that the pump will be the cause of your problem.

Since the original launch of the Vaillant ecoTEC boiler in 2005, the pressure sensor has been through three different revisions. The earliest sensor turned out to have a very high rate of failure, so when Vaillant discovered this problem, it rolled out a sensor to replace it. The problem was due to the fact the early sensor became rapidly blocked with sludge and debris, preventing it from sensing pressure changes when the pump was functioning. This, in turn, would lead to a reported F75 error code from the boiler.

This blockage of the sensor could be caused by two different things. Either, it was as a result of debris and carbon deposits building up inside the filtration system, or because the boiler system had not been properly treated and cleaned during its installation.

How Can The Vaillant F75 Error Code Be Fixed?

Since there are several reasons why the Vaillant F75 error code may appear, it requires a methodical approach to its repair.

  • First, it’s important to establish if the fault is due to the pressure sensor or the pump itself. It may be possible to achieve this by listening to the sound the boiler makes when it has been turned on and is trying to function.
  • The boiler can be reset by pressing the button with a cross flame symbol (the lockout button) then by turning on the heating or running the hot water tap for a demand for heat to be supplied.
  • If you can hear the pump running for several seconds about every twenty seconds, this means the pump is functioning properly. It will sound similar to a low rumbling sound. If you’re able to hear this, it’s likely to be the pressure sensor which is resulting in the Vaillant F75 fault code.
  • If you can’t hear a rumbling sound from the pump when it’s running, it’s likely that the fault is due to the pump itself. You will need to call out a Gas Safe engineer to examine the boiler then replace the pump which is faulty.
  • If the pressure sensor turns out to be the cause of the fault, it’s possible to repair it by stripping out the pressure sensor and then cleaning out the water-block where it’s fitted before a new one can be installed. Since pressure sensors are quite affordable, you should replace it instead of cleaning the old one and trying to use it again.

Is F75 The Only Vaillant Error Code?

F75 is just one of several different error codes that might show up on a Vaillant boiler. If you’re having problems with your boiler, there may be an error code or there may not. If you do see one, you should tell us which error code you see when you call us. We can then be prepared for the right type of repair when we come out to visit your property and rectify your system. You can be confident that we’re a team of highly trained, experienced boiler engineers, so you can rest assured your boiler will be in safe hands if you contact us.

Could I Fix This Fault Code Myself?

The F75 Vaillant fault code is not something you should try to repair yourself. Whether the cause of the fault is the pump or the pressure sensor, you should call our team of Gas Safe registered engineers to rectify the problem for your convenience and your safety.