Boiler shows E03, pump symbol flashing, heating performance reduced

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

Partially seized circulation pump, Air in pump, Faulty pump speed control signal from PCB

Safety: Isolate power. Surfaces may be hot.

Vent pump: If the pump has a vent screw, carefully open it with a cloth to release trapped air (have a tray ready for small water leakage). Retighten securely.
Free the rotor: With power off, remove the pump head cover and gently turn the rotor with a screwdriver to free it if stiff.
Check for noise: When restarted, listen for grinding or humming. Persistent noise indicates wear and the pump should be replaced.
If the pump is mechanically sound, a technician should test the control signal from the PCB.

Medium 3/5

Circulation Pump

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