E04
Aquaflow Phase Loss / Single-Phase Operation Detected (for 3‑phase or inverter models)

Display shows E04 and pump will not start, sometimes accompanied by a humming noise

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Safety Warning

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.

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Possible Causes

One phase missing at supply, Loose phase connection at Aquaflow terminal block, Internal drive output failure on control board

How to Fix / Troubleshooting

Safety first: Isolate power at the main disconnect. Only perform phase checks if you are trained and equipped to work on 230/400V circuits.

  • Verify 3‑phase supply: Using a multimeter, measure voltage between all three line conductors (L1–L2, L2–L3, L1–L3). All readings should be within the specified range and roughly equal.
  • Inspect terminal block: Remove the Aquaflow control box cover and check that all phase conductors are firmly clamped in the terminal block. Tighten any loose screws.
  • Check upstream breakers and contactors: Confirm that all poles of the breaker or contactor feeding the pump are operating and not burned or stuck.
  • Test with known-good supply: If possible, temporarily connect the pump to a verified 3‑phase source to rule out site wiring issues.

If supply is correct and E04 persists, the internal inverter or drive section of the Aquaflow control board may be damaged and typically requires replacement by a professional.

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Repair Difficulty

Professional Required 5/5

Required Part

Aquaflow control board assembly
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