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Understanding the F75 Vaillant Fault Code

If you have a Vaillant boiler, then the F75 fault code may be something you are used to seeing – but what causes it, and how can you fix it? We investigated this fault code and have come up with a handy user guide for you to follow when it comes up on your boiler – read on to find out more!

What Does the F75 Fault Code Mean?

The first thing that you will need to know is what the fault code actually means and where the issue is in your boiler. Vaillant defines the F75 code as one or more of the following problems:

  • Defective pump
  • Defective water pressure sensor 
  • Low pressure within the boiler system
  • Connection of the external expansion vessel to the return

When the code is present, the boiler may still be able to function properly, but there could be an issue with the heating pump or the pressure sensor that needs to be repaired. Unfortunately, working out the exact problem yourself can be difficult, and this fault code typically needs a Gas Safe registered engineer to repair the boiler.

Understanding the Pressure Sensor Error

The EcoTec boiler range is most often the boiler that has the F75 error code when it comes to the pressure sensor. This is mainly due to the fact that when the EcoTec range was released, the pressure sensors used were not the highest quality. Three major upgrades later, new EcoTec boilers do not have as many F75 faults, but if you have an older model, then you may be prone to this problem occurring.

The main reason that the F75 error is so prevalent with these sub-par sensors is that debris would cause a build-up within the system, making the boiler have to work harder and causing the pressure sensor to stop working properly. To try and avoid this issue becoming a reality, you should consider installing magnetic filters to draw the debris out rather than letting it develop. However, if your sensor has already become blocked with a sludge build-up, then this will need to be replaced and the system cleaned to avoid it from reoccurring.

Understanding the Defective Pump Error

If the F75 error is showing because the pump is defective, it is probably because the pump that Vaillant used to use in their systems is not as tough and durable as it is with other manufacturers. Older models will have Wilo pumps, but they have such a poor reputation for failing that Vaillant has now moved away from them.

Newer Vaillant models now use Grundfos pumps that have a reputation for being fairly priced and offering the strength and durability that you need to keep your boiler running. If your system does have the older Wilo pump, then it is worth considering getting it replaced if it has not yet failed.

Working Out the Fault When F75 is Showing

If your boiler is showing an F75 fault code, then you are sure to want to diagnose what the issue may be before paying for an engineer to fix it. Take a look at the following steps to help you get a better idea of what is going on:

  1. First, check your boiler pump to see if it is working properly – if it is, then you can be pretty confident that your issue is the pressure sensor. To know if your pump is running properly, then there should be a slight amount of vibration and a very soft humming noise coming from it – if there isn’t, then your pump may need to be replaced.
  2. If you are sure that your pump is working well, then it’s time to check your pressure sensor. If you can hear noise or feel movement on the sensor, then it could have a build-up of sludge that is causing it to malfunction, and you will need an engineer visit. You can either have it replaced or cleaned out, but often the price is roughly the same, so it may be worth replacing it to have complete peace of mind.

Understanding the Cost of Fixing the F75 Fault Code

Unexpected repair costs for a broken boiler can cause financial uncertainty and worry, leaving many consumers looking for estimated costs to fix the F75 fault code. The actual cost will depend on whether it is your pump or sensor that needs to be replaced, the cost of the parts, how easy it is to be fixed and where you are located in the country. 

The average cost for a high-quality replacement pump can be anywhere between £250 – £300, and the average cost for a replacement boiler sensor is around £175 – £250. However, it is worth getting quotes from a few different companies to find the best price for you.

Commonly Asked Questions About the F75 Fault Code

Still have questions about the F75 fault code? Take a look at these frequently asked questions to get the answers you need:

Can I Fix the F75 Fault Myself?

Unless you are a Gas Safe engineer, you will not be able to fix the F75 fault as you will either need a new pressure sensor or heating pump. Both of these jobs require a professional to complete as there is a risk to your safety should they be incorrectly installed.

Will Resetting My Boiler Get Rid of the F75 Error?

No, but you can reset your boiler once it has been fixed to clear the error code. To do this, you need to press and hold the reset button for a few seconds and then release. 

What Pressure Should My Boiler Gauge Show?

The typical pressure for a Vaillant boiler should be around 1 to 1.5 bar. To check this, simply look for the pressure gauge, which could be either digital or analogue.

Find the Right Support for Your F75 Error CodeIf you need to find an engineer to help fix your F75 error code, then Boilers Prices is ready to help. Our quotation and engineer finding tool is quick and simple to use and will provide you with the details of engineers in your local area. We know that the F75 error code will leave you worrying about your boiler health, but it is usually something that can be dealt with quickly and efficiently when caught early – don’t delay, let us help you find the best engineer today!