F.74 error, boiler reports excessively high pressure, may not start

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

Shorted pressure sensor, Moisture in sensor connector, Wiring short to 5V reference, PCB sensor circuit fault

Safety: Turn off power. Verify actual system pressure on the mechanical gauge.

Checks:

If the gauge shows normal pressure (around 1–2 bar) but the display indicates very high pressure, suspect the sensor.
Inspect and dry the sensor connector if wet.
Check wiring for damage or shorts.
Replace the water pressure sensor if wiring is intact.

If F.74 persists with a new sensor, the PCB is likely at fault and should be replaced by a professional.

Medium 3/5

Water Pressure Sensor

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