Boiler displays F38; the pressure reading is abnormally high or unstable.

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

A faulty water pressure sensor, a blocked sensor port or tube, a wiring fault to the PCB, or a PCB analogue input fault.

Safety: Isolate power and allow the boiler to cool.

Steps:

Compare the digital pressure reading (if available) with the mechanical gauge. If they differ significantly, suspect the sensor.
Inspect the sensor port or connecting tube for sludge blockage and clean carefully.
Test the sensor output with a multimeter according to Protherm specifications. Replace the sensor if readings are incorrect.
If a new sensor does not resolve the issue, the PCB may be faulty and require replacement.

Medium 3/5

Water Pressure Sensor

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