F74 error, water pressure sensor signal too high or out of range

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 sensor wiring, Incorrect sensor type, Internal sensor failure, PCB input fault

Safety first: Isolate power and allow the system to cool.

Compare readings: Compare displayed pressure with a mechanical gauge. If display is much higher, suspect sensor or wiring.
Inspect wiring: Look for shorts between sensor signal and supply wires.
Replace sensor: Fit a new Protherm pressure sensor and test.
PCB check: If a new sensor does not resolve F74, the PCB input may be defective.

Warning: Do not rely on faulty pressure readings for safety decisions; verify with a mechanical gauge.

Medium 3/5

Water Pressure Sensor

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