F.73
Vaillant
Water Pressure Sensor Open Circuit / Fault
F.73 displayed, pressure gauge shows normal but boiler reports low pressure
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Defective water pressure sensor, Loose or corroded sensor connector, Broken wiring to sensor, PCB sensor input failure
How to Fix / Troubleshooting
Safety: Isolate power and allow the boiler to cool before removing any hydraulic components.
Steps:
- Locate the water pressure sensor on the hydraulic block.
- Inspect the connector for corrosion or loose fit; clean and reseat.
- Check wiring continuity between sensor and PCB.
- If wiring is sound, replace the water pressure sensor.
If the new sensor does not resolve the issue, the PCB may be faulty and should be replaced by a technician.
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Repair Difficulty
Medium
3/5
Required Part
Water Pressure Sensor
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