Controller displays E05 and pump stops shortly after starting, especially under high load.

Safety first: Turn off power before adjusting plumbing or opening the pump.

Hydraulic system checks:

• Open all valves: Confirm suction and return valves are fully open. Avoid throttling flow on the discharge side with the pump at maximum speed.
• Clean filtration system: Backwash sand filters or clean/replace cartridge filters to reduce system pressure.
• Check for obstructions: Inspect return lines and check valves for blockages that could increase head pressure.

Controller and motor checks:

• Reduce speed: On Speck variable-speed models, lower the maximum RPM setting and observe current draw if an ammeter is available.
• Monitor current: Compare measured current to the motor nameplate rating. If current is high even at normal head, suspect motor winding issues.

If E05 recurs with clean hydraulics and normal head pressure, the motor or drive electronics may be failing and should be inspected by a service technician.