Unit displays E05 and stops; water temperature reading is erratic or clearly incorrect.

Safety first: Turn off power and close isolation valves if you will open any plumbing connections.

• Locate outlet sensor: Find the water outlet temperature sensor on the SPRSUN heater (usually inserted into a sensor well on the outlet pipe).
• Check seating: Ensure the sensor probe is fully inserted into the well and secured with its clip or clamp.
• Inspect connector: Trace the sensor cable to the control board and verify the plug is firmly connected and free of corrosion or moisture.
• Dry and reseat: If moisture is present, dry the connector, apply a small amount of dielectric grease if available, and reconnect.
• Test operation: Restore power and see if the temperature reading is stable and E05 clears. If not, replace the outlet temperature sensor with the correct SPRSUN part.