Pump display shows ERR4 and will not start; sometimes appears after a power surge or lightning storm.

Safety first: Isolate power at the breaker and wait at least 5 minutes for internal capacitors to discharge before opening any covers.

• Power cycle the unit: Turn off the breaker for 2–3 minutes, then restore power and attempt to start the pump. Transient faults may clear.
• Inspect external wiring: Check that line, neutral and earth are correctly connected and tight at the pump terminal block. Incorrect wiring can trigger drive faults.
• Check for surge damage: Look for burn marks or a burnt smell around the control housing. If present, do not attempt further operation.
• Reset controller (if menu allows): Some AstralPool controllers have a factory reset option in the settings menu. Perform a reset following the user manual, then reprogram schedules.

ERR4 usually indicates an internal electronics failure. Replacement of the power/control PCB or complete drive module is typically required and should be done by an authorized AstralPool service agent.