Control panel displays E03 and the heater shuts down

Safety first: Turn off and unplug the spa. Allow the water to cool to a safe temperature before working on the unit.

• Allow cooling: Leave the spa unplugged for at least 30–60 minutes to let internal components and water temperature drop.
• Remove cover while heating: When restarting, keep the spa cover partially open for a while to prevent heat buildup, especially in hot weather.
• Check water circulation:
  • Verify that the filter cartridge is clean and not restricting flow.
  • Ensure all inlet/outlet fittings are fully open and not blocked by debris.
• Inspect for dry firing risk: Confirm that the water level is above the minimum line and that there are no airlocks in the system.
• Reset and test: Plug the spa back in, clear the error according to the Bestway manual, and monitor temperature rise. If the unit overheats again quickly, stop using it.

Repeated E03 errors indicate a failing high-limit thermostat, thermal fuse, or control board. These components are inside the sealed heater/control assembly and should be replaced by a professional.