Lay-Z-Spa shows E03 and shuts down heating; unit may beep repeatedly.

Safety first: Unplug the spa and allow the water and heater to cool completely before working on it. Hot water and components can cause burns.

• 1. Let the spa cool: Leave the unit powered off for at least 30–60 minutes to allow the internal high-limit sensor to reset.
• 2. Check water circulation: With the spa cooled and powered back on, run only the filter function. Look for strong water movement from the outlet jets. Weak or no flow indicates a blockage or pump issue that can cause overheating.
• 3. Clean filters and check hoses: Remove and clean/replace the filter cartridge. Inspect hoses and inlet/outlet ports for obstructions. Ensure the spa is filled to the correct level.
• 4. Descale the heater path: If you live in a hard-water area, internal scale can cause hot spots. Use a Lay‑Z‑Spa‑approved descaling solution circulated through the system according to the product instructions, then flush thoroughly.
• 5. Restart and monitor: After cleaning and descaling, restart the heater and monitor temperature rise. If E03 reappears quickly, the high-limit thermostat or heater control may be faulty.
• If E03 persists: The overheat sensor, thermal fuse, or heater control relay may be defective. These are internal safety components and should only be serviced by a qualified technician. In most cases, the heater assembly or entire pump/heater unit must be replaced.