Pump display shows E03 and motor does not run, sometimes accompanied by humming noise

Safety first: Turn off and lock out the main disconnect feeding the pump. Use a meter only if you are trained to work on live circuits.

• Check upstream protection: Inspect the three‑pole breaker or fuses feeding the Saci pump. Replace any blown fuses with the correct rating and reset tripped breakers after identifying the cause.
• Inspect terminal box: Remove the motor terminal cover and verify all three phases (L1, L2, L3) are firmly connected. Tighten any loose screws and look for burnt or discolored terminals.
• Measure phase voltages: With power restored (only if qualified), measure L1–L2, L2–L3, and L1–L3. All should be within the specified range and balanced. If one phase is missing, have an electrician correct the supply.
• Check contactor: If the pump is controlled via an external contactor, inspect the contacts for pitting or burning and ensure all three poles are closing properly.

If E03 persists with balanced three‑phase supply, the internal motor protection or control PCB may be defective and should be replaced by a technician.