Display shows E2 and unit shuts down; water may briefly warm then go cold.

Safety: Turn OFF power at the breaker and close the water supply before opening the heater.

Inspection and repair:

• Remove the front cover of the Eemax heater.
• Locate the outlet thermistor on the hot water outlet side of the heat exchanger. It will resemble the inlet sensor but mounted on the outlet pipe or heat exchanger outlet.
• Check the wiring harness from the outlet sensor to the control board. Look for discoloration, brittle insulation, or loose connectors. Reseat the connector.
• Use a multimeter to measure the thermistor resistance at room temperature and compare to Eemax specifications. An open or shorted reading indicates a bad sensor.
• Replace the outlet thermistor with the correct Eemax outlet temperature sensor if readings are out of range or if the sensor is physically damaged.
• Inspect for signs of overheating or scale at the outlet; excessive scale can cause localized overheating and sensor failure. Descale the unit if needed.
• Reinstall the cover, open the water supply, restore power, and run hot water to confirm the E2 code is cleared.

If the sensor and wiring are good but E2 remains, the main control board may be defective and should be tested or replaced by a professional.