Spa overheats beyond the set temperature without showing an error; water feels too hot.

Safety first: If water feels excessively hot, unplug the spa immediately and do not use it until the issue is resolved.

• Verify temperature:
  • Use an independent waterproof thermometer to measure water temperature.
• Inspect sensor placement:
  • Ensure the water temperature sensor is correctly mounted on the heater tube or in the flow path.
• Replace sensor:
  • If readings are inaccurate, install a new Avenli water temperature sensor.
• Check for stuck relay:
  • If the heater continues to warm water even when the display shows heating OFF, the heater relay on the PCB is likely stuck closed.
  • Replace the control box assembly in this case.