F73 displayed, water pressure sensor signal too low or missing

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.

Possible Causes

Defective pressure sensor, Sensor not filled with water (air lock), Loose connector, Broken sensor diaphragm

Safety first: Turn off power and allow the system to cool before opening any water connections.

Check system pressure: Confirm actual pressure on a mechanical gauge. If low, top up and bleed air.
Inspect sensor: Locate the water pressure sensor and check for leaks or damage.
Reseat connector: Disconnect and reconnect the sensor plug.
Replace sensor: If F73 persists and actual pressure is normal, replace the pressure sensor with the correct Protherm part.

Warning: Depressurize the system before removing the sensor to avoid water discharge.

Medium 3/5

Water Pressure Sensor

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