The Vaillant Boiler F75 error is one of the most frequently encountered fault codes for Vaillant models, especially the EcoTEC range. If you're seeing this code, your boiler has detected a problem with the water pressure sensor or pump — and has shut down as a safety measure.

Signs You Might Notice Before the F75 Error

Before the F75 code appears on your boiler display, you may notice symptoms such as unusual noises from the pump, inconsistent heating, or radiators taking longer to warm up. These early warning signs mean it’s time to get your boiler checked to avoid complete shutdown.

How Our Engineers Diagnose the F75 Fault

Our qualified technicians use specialized diagnostic tools to test the water pressure sensor and central heating pump. We also check for airlocks, sludge buildup, and pressure drops to pinpoint the exact cause of the fault quickly and accurately.

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• Certified Vaillant boiler engineers with years of experience
• Same-day or next-day callouts available in Liverpool
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• Genuine Vaillant parts and manufacturer-approved repairs
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What Does the F75 Error Code Mean?

F75 means your boiler can't detect the expected pressure increase when the pump starts. Typically, this is due to:

• A faulty or stuck water pressure sensor
• An air-locked or seized central heating pump
• Low system pressure or air in the system

This issue needs prompt attention, especially in colder weather, to avoid losing hot water or heating entirely.

Common Causes of F75 on Vaillant Boilers

• Pressure Sensor Failure: These sensors are sensitive and known to fail with age or water contamination.
• Central Heating Pump Faults: The pump may not start, or its internal components might be worn or jammed.
• System Airlocks: Air trapped in the system can disrupt pressure readings and flow.
• Low Water Pressure: The system may be below the required 1.0–1.5 bar range.

Can I Fix the F75 Error Myself?

While some checks are safe for homeowners, most F75 issues require a professional. Here's what you can do before calling an engineer:

• Check the boiler pressure — top it up using the filling loop if it's under 1 bar.
• Reset the boiler after topping up — press the reset button once.
• Bleed radiators to remove trapped air (have a towel and bleed key ready).

Important: If you’re unsure or the fault reappears, stop and get expert help. Continued resets won’t solve an underlying mechanical issue.

Professional F75 Repair: What to Expect

Our engineers commonly repair F75 faults by:

• Replacing the pressure sensor with an updated version
• Unseizing or replacing the Grundfos central heating pump
• Flushing the system to remove sludge and air

We only use manufacturer-approved parts and carry out thorough diagnostics to ensure your boiler operates safely and efficiently.

Prevent Future F75 Errors

Regular servicing is the best way to avoid repeat F75 faults. During a boiler service, we will:

• Check the pump and sensor function
• Top up and balance system pressure
• Clean out any debris or blockages

F75 can often be a warning sign of system debris or poor water quality. Adding a magnetic filter and using system inhibitor fluid can greatly reduce the risk of future breakdowns.

Download the Vaillant Boiler Manual

You can refer to the official Vaillant installation and servicing manual for your model. Download it here (PDF).

FAQs – Vaillant Boiler F75

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