F75 Vaillant Boiler Fault: What Does F75 Fault Code Mean and How to Fix It?

F75 Vaillant Boiler Fault: What Does F75 Fault Code Mean and How to Fix It?

Seeing an F75 fault on your Vaillant boiler? Read this article to discover what the F75 fault code means and how to fix it!

If you live in a cold country, you know how important boilers and heating systems are. Without them, we’d be wrapped up in a thousand layers and still freezing our toes off. So, once an error appears in your boiler, you need to quickly understand what it means so that you can get your boiler up and running as soon as possible.

Accordingly, we’ll be discussing what the F75 error code means on a Vaillant boiler. We’ll also tell you what prompts its appearance and how you can diagnose the issue. So, keep reading to learn all these vital pieces of information and discover how to fix the F75 error.

What Does the F75 Vaillant Error Code Mean?

Quite simply, the F75 error code means that your boiler isn’t able to detect any pressure changes when the pump starts working. This means that your boiler won’t be able to circulate water throughout your pipes and heating system.

Now, there are a few different reasons why your boiler may fail to detect the water pressure. That’s why it’s essential you learn what they are so that you’ll be able to fix the issue. So, let’s take a look at what those reasons can be, shall we?

Reasons for a Vaillant F75 Error Code

Typically, the F75 error code appears due to a fault with one of the following; the pressure sensor, the boiler pump, or your heating pipeworks. Let’s see how each of these components will cause an F75 error.

Faulty Pressure Sensor

Over time, the water pressure sensor may become clogged with dirt, debris, and limescale. This buildup can be very severe to the degree that it prevents the sensor from reading pressure changes and responding to them appropriately.

Generally, if you’re not getting hot water, you can tell that the problem lies with your sensor if you can hear the pump working while the boiler is on. In that case, you’ll need to either clean the pressure sensor components or replace the entire apparatus.

Thankfully, though, the cost of getting a new sensor isn’t too steep, so if the issue is really with your sensor, you’ll be able to easily replace it.

Damaged Pump

Unfortunately, some of the earlier models of the Vaillant boiler were fitted with pumps that were of poor quality. These pumps can frequently suffer from leaks and splits, which, of course, means that they won’t be able to get enough water into and out of the boiler. Accordingly, no pressure changes are detected, and the F75 error will occur.

Fortunately, in 2005, Vaillant began fitting their newer models with high-quality pumps from a different manufacturer. So, if your Vaillant boiler is from before 2005, it’s highly likely that the F75 error is due to a faulty pump. You can confirm that the issue lies with your pump if you can’t feel or hear any sounds coming from your boiler when it’s turned on.

Leak in Heating System

If the pipework of your heating system has got a leak somewhere, this will prevent water from reaching your boiler, and no pressure will be detected by the sensor. Generally, the leak can happen due to direct damage or prolonged wear and tear.

Still, it’s a bit uncommon for the F75 error to be caused by this problem. So, only start looking for leaks when you’re absolutely sure that both the sensor and the pump are 100% functional.

How to Fix an F75 Error Code on Vaillant Boiler

As we said, the F75 code can be due to a variety of reasons. So, the first step in fixing the error should be finding out where the problem stems from.

Accordingly, you should start by resetting your boiler by pressing the lockout button. Then, run a hot tap or turn on your house heating, and listen closely.

If you hear a rumbling sound and feel a vibration coming from the boiler, this means that your pump is perfectly fine and that the sensor is most likely the issue. In that case, you should simply substitute your sensor with an adequate replacement.

Take care that this rumbling sound isn’t continuous. It’ll only last for a few seconds; then, it’ll fall silent. Then, after 20 seconds or so, it’ll start running again. So, don’t be alarmed if the rumbling sound disappears.

Okay, so if there’s a buildup in the sensor, you can try cleaning it first and seeing if the sensor will work again. However, more often than not, the sensor will fail again, leaving you with the same frustrating error.

Conversely, if you don’t hear any rumbling sound when running a hot tap, this indicates that the pump is the problem.

Now, if you know your ways around boilers, you can try repairing or replacing the pump by yourself. However, it’s best you leave it up to the professionals to avoid doing any extra damage to your boiler.

The good news is that pumps aren’t that much more expensive than pressure sensors. Accordingly, you can easily replace it and spare yourself the trouble that comes with repaired parts.

Finally, if both your pump and sensor are okay, and you’re convinced that the problem involves a leak in your heating system, you need to hire professionals. Only they will be able to locate and repair the leak in a safe way that’ll spare you and your home from significant damage.

F75 Vaillant Boiler Fault – Conclusion

To sum up, we can say that the F75 error code on a Vaillant boiler means an issue with pressure detection. This is generally due to a faulty sensor or pump. However, it can also be due to a leak in your heating system.

In most cases, you’ll probably end up replacing the sensor or pump. Still, it’s always best to have a professional have a look first if you’re not sure where the problem is coming from.