Vaillant F75 Fault

Vaillant F75 Fault

The Vaillant F75 error code is a common issue that indicates the boiler’s pressure sensor or the water pump is not working correctly. Specifically, this fault arises when the boiler’s control unit detects no pressure change within the system after the pump has been activated, suggesting a problem with the water circulation or the sensor itself. Understanding the causes and solutions for this error is essential for restoring your boiler to proper operation.

Causes of the F75 Error Code

  1. Faulty Pressure Sensor: Over time, the pressure sensor can become blocked or fail, preventing it from detecting pressure changes in the system.
  2. Pump Failure or Seizure: If the pump is seized or not operating correctly, water cannot circulate through the system, leading to a lack of pressure change.
  3. Airlocks in the System: Air trapped within the heating system can impede water flow and pressure buildup, resulting in the F75 error.
  4. Low Water Pressure: Although the primary issue is usually with the sensor or pump, low water pressure in the system can exacerbate the problem.

Troubleshooting and Resolving the F75 Error Code

  1. Repressurize the System: Ensure that the system pressure is within the recommended range (typically between 1.0 and 1.5 bar). Adjust the pressure if it’s too low.
  2. Bleed Radiators and the System: Release any trapped air in the radiators and heating system to eliminate potential airlocks that could affect water circulation.
  3. Check and Clean the Pressure Sensor: The pressure sensor may need to be cleaned or replaced if it’s blocked or malfunctioning. This task should be performed by a professional due to the complexity of the boiler’s internal components.
  4. Inspect the Pump: Verify that the pump is operational. You may hear it running, or a professional technician can check its functionality. A seized or faulty pump will likely need to be repaired or replaced.
  5. Reset the Boiler: After addressing potential issues, reset the boiler to see if the error clears. This can sometimes resolve the fault if temporary glitches caused the error.
  6. Professional Diagnosis and Repair: Due to the technical nature of the F75 fault, involving critical components like the pressure sensor and water pump, it’s advisable to seek help from a Gas Safe registered engineer. A professional can accurately diagnose the issue and carry out necessary repairs or replacements safely and effectively.


The Vaillant F75 error code signifies a problem related to the pressure sensor or water pump, affecting the boiler’s ability to circulate water properly. While homeowners can perform some basic checks and adjustments, resolving this error often requires professional intervention. Regular maintenance and servicing by a qualified technician c