The Vaillant F75 fault code error and how to clear it

Is your Vaillant boiler displaying the F75 error code? If so, then you’re probably without hot water or central heating. Thankfully, the Vaillant F75 fault code gives some indication of the problem, so a registered Vaillant Advance boiler engineer can quickly get to the heart of the problem. Read on to find out what the F75 Vaillant boiler fault code stands for and what you should do when it’s shown on the display panel.

What does a Vaillant F75 fault code mean on your boiler?

The Vaillant F75 error code will display when your boiler can’t register a pressure change when the pump turns on. This usually happens because of a faulty pump or if there’s a problem with the water pressure sensor. Our experts say it could also be due to a leak in the connected pipes, but this is less likely and more commonly a reason for the F22 fault code.

How do I fix the F75 on a Vaillant boiler?

Because an F75 boiler error code can arise for multiple reasons, you’ll need a Gas Safe-registered engineer to diagnose the cause of the fault. We recommend choosing someone on the Vaillant Advance installer scheme, such as Aspect, because of their experience working with Vaillant boilers.

The engineer will need to check the condition of both the boiler pump and the pressure sensor. They’ll explain why the Vaillant fault code (F75) has occurred and what must be done to resolve the issue. This could mean either a replacement pump or a new pressure sensor.

Tip: If the F75 was caused by dirt on the sensor, it’s usually best to get it replaced rather than cleaned due to the costs probably working out the same.

Is my boiler’s pump defective or is it the pressure sensor?

We always recommend that you speak with a Gas Safe engineer the moment you see the Vaillant F75 fault code pop up on your boiler’s display. However, there are ways to help diagnose the cause of the fault:

1. Press the reset button on your boiler and wait a few minutes.
2. Try to get the heat going, either by running a hot tap or via the central heating thermostat.
3. Listen closely for a hum and feel for a vibration. This will be the pump turning on.
4. If you reset the boiler but don’t hear anything at all, then you likely have a broken pump.
5. If you hear the pump turn on and switch off again, it’s probably an issue with the pressure sensor.
6. Contact a Gas Safe-registered engineer to confirm the issue. They can then get your hot water and central heating system working again.

What causes a pump to fail inside a Vaillant boiler?

Your boiler’s heating pump could fail due to its age. In addition, older Vaillant EcoTEC models featured less reliable pumps that would break down more frequently than the ones commonly used today. Vaillant advises, their boilers last between 10 and 15 years, so if you have an old EcoTEC model, an F75 boiler fault code may serve as a good indicator that it’s time to upgrade.

What causes a faulty pressure sensor?

Generally speaking, Vaillant boilers built up to 2010 were more prone to pressure sensor issues. Newer models suffer less from faulty pressure sensors, but it does still happen.

One issue that can cause problems in pressure sensors is known as magnetite. Known to reduce the efficiency of central heating systems, this dark sludge (which forms as a heating system suffers from internal corrosion) can collect on the boiler pressure sensor, making it unable to register pressure changes. Because magnetite is partly made of scale, hard water can contribute to a Vaillant F75 fault code.

How can I prevent the Vaillant boiler F75 fault code error?

Annual servicing is the best way to avoid boiler problems. Your engineer will check for leaks and component damage, and they can provide a very basic clean to wipe debris off the pressure sensor. Getting your boiler serviced each year is required for most manufacturer warranties, including Vaillant. So, sticking to your annual servicing schedule can save you money in the long run.

Another way to protect your boiler is with a power flush, which removes magnetite that can cause a pressure sensor to fail. The engineer pumps a cleaning solution through the central heating system. They then add a chemical inhibitor that helps reduce corrosion. In turn, you’ll be less likely to experience a Vaillant F75 error code in the future. You can learn more about power flushing here.

Need a new boiler? Remember to pick a Vaillant Advance installer. They can fit an efficient new model, complete with an extended warranty – up to a max of 10 years on selected models. This warranty will cover faulty pumps and sensors, but not the replacement of a sensor affected by magnetite.

If you have a Vaillant F75 fault code and find yourself without hot water, we’ll be happy to help. We’re available 24/7 and can send an engineer to your location in under an hour when you need priority attendance.