Control panel displays E01 and the NetSpa hot tub will not heat; pump may still run in filtration mode.

Safety first: Unplug the NetSpa spa from the mains before opening any panels or handling water connections. Never work on the spa while you are in the water.

• Check water level: Ensure the water level is above the minimum line indicated on the spa wall. Low water can trigger low-flow protection.
• Clean or replace the filter cartridge: Remove the filter cartridge from the NetSpa filtration housing, rinse it thoroughly from inside out with a garden hose, and reinstall. If the cartridge is deformed or heavily soiled, replace it with a compatible NetSpa filter cartridge.
• Bleed air from the system: With the spa unplugged, slightly loosen the filter housing cap or a hose connection at the highest point to allow trapped air to escape, then retighten. Refill water if needed.
• Check intake and outlet fittings: Inspect the suction and return fittings on the spa wall for debris, leaves, or toys blocking flow. Remove any obstruction.
• Test the massage/circulation pump: Plug the spa back in and run the filtration or massage mode. If flow is still weak, the internal circulation/massage pump may be failing or obstructed and may need cleaning or replacement.

If E01 persists after these steps, discontinue use and contact a qualified spa technician to test the flow sensor and pump assembly.