MSPA spa shows E5 and stops heating; sometimes accompanied by pump stopping.

Safety first: Disconnect power and allow the spa to cool before opening any covers.

• Check for flow issues: Before assuming heater failure, clean the MSPA filter, check water level, and ensure strong water flow from the outlet. Restricted flow can overheat the heater.
• Inspect heater housing: Look for signs of discoloration, melting, or burning smell around the heater tube on the MSPA motor/control unit. Any such signs indicate overheating and the heater assembly should be replaced.
• Descale (if accessible): If your model allows heater removal, inspect the inside for heavy scale. Descale with an appropriate solution, rinse thoroughly, and reassemble. If the internal thermal fuse has opened, the heater will still not work and must be replaced.
• Replace heater assembly: If E5 persists and there is no flow problem, replace the complete MSPA heater assembly (including element and thermal fuse). Transfer any seals or gaskets as per the service manual and ensure all hose clamps are tight to prevent leaks.

Because heater circuits carry mains voltage, if you are not confident, contact an MSPA service center.