Vaillant Pressure Sensor Explained

What is a Vaillant Pressure Sensor?

The Vaillant Pressure Sensor, also referred to as a water pressure sensor, serves as a digital pressure monitoring system built into Vaillant boilers. It is responsible for detecting the pressure accurately within the heating system and relaying this data to the boiler's electronics.

Key Features of the Vaillant Water Pressure Sensor

• Detects and monitors water pressure digitally.
• Communicates pressure levels to the boiler's control unit.
• Ensures the system maintains optimal pressure to operate safely and efficiently.

If you're experiencing any issues with your boiler sensor, it's best to seek assistance from a professional boiler repair service right away.

What is the Location of the Vaillant Pressure Sensor?

It varies depending on the specific boiler model:

• Older Models: Located at the bottom left corner of the boiler.
• Newer Models (e.g., Vaillant ecoTEC series): Positioned below the heat exchanger on the inlet pipe.

Importance of the Vaillant Pressure Sensor

The pressure sensor ensures that your boiler maintains the proper pressure range, typically between 1 and 1.5 bar. If the pressure is too high or too low, the boiler might shut down as a safety precaution.

Common Vaillant Pressure Sensor Faults

Vaillant boilers are equipped with an error code system that helps diagnose pressure-related issues. The most common pressure sensor fault codes are:

F73 – Faulty Pressure Sensor

This code indicates that the pressure sensor is not accurately reading the system's pressure. Possible causes include:

• A defective pressure sensor.
• Loose or damaged wiring.
• Corrosion (system sludge or magnetite buildup).

F75 – Pressure Detection Failure

An F75 Vaillant error occurs when the boiler cannot detect a pressure increase after the pump is activated. This may be caused by:

• A blocked or failing pressure sensor.
• Malfunctioning pump.
• Low system pressure or internal blockages (e.g., sludge).

Causes of Pressure Sensor Faults

Several factors can lead to Vaillant pressure sensor errors, including:

• Faulty Pressure Sensor: Over time, the sensor may become worn out or damaged, necessitating replacement.
• Wiring Issues: Loose, corroded, or damaged wiring between the sensor and the control unit can disrupt communication.

• System Sludge or Magnetite: Corrosion or debris in the heating system can block the sensor or affect accuracy.
• Low Water Pressure: If the system pressure falls below the recommended level, the boiler could display fault codes.
• Other Faulty Components: Problems with the pump, expansion vessel, or control unit (PCB) can indirectly cause pressure sensor faults.

Troubleshooting and Repair

If the Vaillant Pressure Sensor on your boiler is showing error codes, follow these steps to troubleshoot the issue:

Use the display panel to check whether the pressure is within the recommended 1–1.5 bar range. If the pressure is low:

• Top up the pressure manually using the filling loop.
• Monitor the pressure after filling to ensure it stays stable.

Check the wiring connected to the pressure sensor and control unit for any visible damage, loose connections, or signs of corrosion. Tighten or repair as necessary.

Attempt a boiler reset to clear temporary error codes. However, if the issue persists, it likely requires further investigation.

• Disconnect the sensor's wires and use a multimeter to test for resistance or continuity.
• Observe the boiler's pressure reading during pump activation. A healthy sensor should show roughly a 0.3-bar pressure increase.

If the fault continues, consult a qualified gas heating engineer. They can diagnose complex issues, replace parts, and ensure the boiler operates safely.

Explore our ‘Boiler Error Codes’ blog section to understand what common error messages mean and how to fix them.

Why Trust Serviceteam for Boiler Repairs?

At Serviceteam, we specialise in comprehensive boiler repair and boiler maintenance services, including Vaillant pressure sensor replacements.

Here's why you should call us:

• Experienced Engineers: All our technicians are Gas Safe registered, ensuring professional and safe repairs.
• Affordable Prices: Competitive pricing with no hidden surprises.
• Guaranteed Workmanship: All heating repairs come with a guarantee for your peace of mind.

If you're experiencing issues with your Vaillant boiler, don't wait for the problem to get worse. Contact Serviceteam and get support from a professional gas heating engineer today, and we'll get your heating system back in top shape!

Book a Professional Boiler Repair Now

FAQs About Vaillant Pressure Sensors

Yes, in most cases, a blocked sensor can be removed and cleaned, especially if system sludge or magnetite caused the block. However, since the sensor is relatively inexpensive, many professionals recommend replacing it for long-term reliability.

The sensor is typically located on the return pipe near the heat exchanger. On newer models, it is positioned slightly behind the plastic air intake (connected to the gas valve), making it less visible.

• The boiler displays error codes (F73 or F75), and troubleshooting does not resolve the issue.
• The pressure gauge or digital display shows no change despite adjustments to the pressure.
• The boiler fails to detect pressure changes when the pump is activated.