Atlantic water heater shows E2 and stops heating; display may show abnormal temperature readings.

Safety: Turn off power at the breaker and close the cold water supply valve before working on the heater.

• Locate the outlet temperature sensor (often mounted near the hot water outlet connection or on the upper part of the tank on Atlantic digital models).
• Unplug the sensor from the control board and check resistance with a multimeter at room temperature. Compare with the specification on the Atlantic rating plate or technical sheet.
• Clean any oxidation on the connector pins and ensure the plug seats firmly into the control board.
• If resistance is out of range or unstable when you gently move the cable, replace the sensor with a genuine Atlantic outlet NTC probe.
• Inspect the cable for pinched or burned sections; replace the harness if damaged.
• If a known-good sensor still triggers E2, the control board is likely defective and should be replaced as a complete Atlantic electronic control module.