Dealing with a temperamental boiler can throw a spanner in your cosy home life, especially when the mysterious error code F75 pops up on the display. 

The key to unlocking this boiler puzzle lies within understanding what F75 is trying to tell us – it’s not just random numbers but an SOS signal indicating a water pressure sensor or pump problem.

By shedding light on this topic, this article will guide you through clearing that error code and avoiding future boiler problems. Keep reading; resolution awaits!

Boiler error code display on boiler

Key Takeaways

  • F75 on a Vaillant boiler indicates a pressure sensor or pump problem, where the system can’t detect water pressure properly.
  • Common causes include a blocked or damaged pressure sensor, a failing pump, or leaks in the heating system that lower water pressure.
  • Fixing an F75 error involves checking for leaks, resetting the boiler, maintaining correct water pressure, and calling a Gas Safe registered engineer if needed.

Understanding the F75 Error Code on Vaillant Boilers

The F75 error code on a Vaillant boiler signals a problem with the water pressure or the pump. This code pops up when the boiler’s control unit doesn’t detect an increase in pressure as the pump kicks in.

It’s like your boiler is trying to move water, but something is blocking its path or it can’t get enough oomph.

A gas safe registered engineer should take a look to sort this out. They’ll check if dirt or limescale has jammed the pressure sensor, stopping it from noticing that crucial pressure change.

Sometimes, they find that internal damage has hit the pump, so it can’t push water through your heating system properly.

If you see this error, a quick response matters to get your hot water flowing again. Next up: let’s explore why F75 errors happen and how you might fix them.

Common Causes of the F75 Error Code

The F75 error code on Vaillant boilers can be caused by a faulty pressure sensor, a damaged pump, or a leak in the heating system. These issues can lead to a loss of pressure and result in the boiler shutting down as a safety measure.
Faulty Pressure Sensor
A clogged pressure sensor often leads to the F75 error in a Vaillant boiler. This happens when dirt blocks the sensor, and it can’t detect the right water pressure. It’s crucial for boilers to measure this accurately, or they don’t work well.

Heating engineer fixing boiler

To fix this, you need to find and clean the sensor. Sometimes cleaning won’t be enough if the damage is too bad. In that case, replacing the pressure sensor is your best bet for getting your heating back on track without further trouble.

Boiler service techs see faulty sensors all the time; it’s a common problem. You must act fast if your boiler displays an F75 code because of a faulty sensor. Ignoring it means more damage over time.

Regular checks can prevent these errors from popping up unexpectedly and save you money in the long run.

Damaged Pump

Your boiler’s pump is crucial; it moves hot water through the system. If this pump gets damaged, you might hear a rumbling sound. This noise suggests something’s wrong inside. Without a working pump, your heating won’t work properly and could lead to an F75 error on your Vaillant boiler.

You need to act fast if you suspect a faulty pump. Call a Gas Safe Registered engineer to check the pump and replace it if needed. Don’t try fixing it yourself as this could be dangerous and may go against health and safety rules.

Only professionals should handle gas appliances for your safety and peace of mind.

Leak in the Heating System

Leaks in your heating system can lead to big trouble with your boiler. A small drip or crack lets water escape, which means the pressure drops. When this happens, the pump must work harder to move water through the pipes.

If it works too hard, it could break down and cause an F75 error on your Vaillant boiler.

Detecting a leak early stops bigger problems later on. Look for wet spots near radiators or pipes as a sign of trouble. Fix leaks quickly to keep your boiler’s pump in good shape and avoid that dreaded F75 code flashing up on your display!

Top Tip:  Regular servicing is the best way to avoid most boiler problems, including the F75 error code.

How to Resolve the F75 Error Code Issue

Fixing the F75 error on your Vaillant boiler involves checking the pump and pressure sensor. Here are steps to solve the problem:

  • First, check if there’s a heating system leak. Look for any water around your pipes, radiators, and boiler.
  • Reset your boiler by pressing the lockout button. This may clear the error temporarily.
  • See if the pressure in your system is correct. It should be around 1.0 to 1.5 bar when cold.
  • If low, refill your system using the filling loop until you reach the right pressure.
  • Examine the pump for any blockages or damage. You may find debris that stops it from running smoothly.
  • Give it a gentle tap to dislodge any trapped air or dirt hindering its movement.
  • Listen for unusual noises that suggest your pump might be struggling to work properly.
  • Contact a Gas Safe Registered engineer if these steps don’t fix the issue. They can replace a faulty pump safely.

Preventing Boiler Error Codes: General Maintenance Tips

  • Schedule an annual service. A Gas Safe engineer will inspect your boiler and fix small issues before they become big problems.
  • Check the pressure gauge. If it’s too low or high, adjust it to the correct level as stated in your boiler manual.
  • Bleed radiators yearly. This removes trapped air, helping your heating system work better.
  • Look for leaks often. Fix any you find right away to avoid damage to your boiler pump and other parts.
  • Clean the external parts of your boiler. Dust and dirt can cause faults if they get inside the system.
  • Test the thermostat. Make sure it responds well so that your combi boilers don’t overwork.
  • Protect pipes from freezing. Insulate them to prevent the cold from causing a blockage or burst pipes.
  • Keep an eye on error codes. They warn you when something is wrong so you can act fast.
  • Use a magnetic filter with your boiler. It catches rust and debris that could harm the pump and sensors.

Still Need Assistance?

If you are still struggling and having problems with your boiler, Kentish Plumbers are here to help you. Our friendly Gas Safe engineers are here to fix it for you.

Remember, regular checks stop errors from happening. Take care of your boiler and it will take care of you!


It might be possible to reset the boiler, but if you’re unsure, it’s always safest to call a professional engineer who knows about boilers and fault detection.

The F75 error keeps happening because there might be a problem with the pump or something blocking the system, not letting water flow properly.

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