MSPA spa stops heating and shows E2; water may feel much hotter or colder than the set temperature.

Safety first: Disconnect power and allow the spa water to cool below 35°C before touching any components.

• Check water level: Ensure the spa is filled to the recommended line. Low water level can cause localized overheating at the heater.
• Inspect water flow: Run the filtration/circulation mode (if available) and feel for strong water movement from the outlet jets. Weak flow can cause heater overheat. Clean or replace the MSPA filter cartridge and remove any debris from the suction and return fittings.
• Descale heater: If you live in a hard water area and the spa has been used extensively, limescale can insulate the heater. Drain the spa, remove the heater assembly (if user‑serviceable), and descale using a manufacturer‑approved descaling solution. Rinse thoroughly before reassembly.
• Reset high-limit (if accessible): Some MSPA models have a manual reset high‑limit switch on the heater housing. With power off and water cooled, press the small red or black reset button if present.
• Sensor/PCB check: If E2 appears immediately on startup even with cool water, the high‑limit sensor or control PCB may be faulty. Inspect the high‑limit sensor wiring and connector on the control box. Replace the MSPA high‑limit temperature sensor if wiring is intact but readings are incorrect.

If the error recurs after cleaning filters, ensuring proper water level, and checking sensors, the heater or main control PCB may need professional diagnosis.