E05 error code appears; heater and pump functions are disabled.

Safety first: Always unplug the spa before adding or draining water near the pump/heater unit.

• Verify water level: Ensure the spa is filled to at least the MIN line on the inner wall. Top up with water if needed.
• Remove airlocks: With power off, gently rock the spa side-to-side to release trapped air from the plumbing. Loosen the air bleed valve (if present) on the pump/heater until water appears, then retighten.
• Check filter housing: Make sure the filter housing is fully submerged and not drawing air. Tighten the filter cover and ensure the O-ring is seated correctly.
• Restart system: Plug the spa back in, run the filtration mode only for several minutes to confirm steady water flow, then enable heating.
• Persistent E05: If the error returns with correct water level and good flow, the internal flow/level sensor may be defective and the pump/heater unit may require service or replacement.

Warning: Never run the heater when the spa is empty or partially filled. This can permanently damage the heater and create a fire hazard.