Atlantic water heater shows E40 and heating is disabled; may be accompanied by a water leak.

Safety: Turn off power and close the cold water supply. Be prepared for possible water discharge.

• Inspect the area under the heater and the drip tray leak sensor (if equipped) for standing water.
• Identify the source: check the tank flange, dielectric unions, safety group, and hot/cold connections for leaks.
• Repair or replace leaking components (e.g., Atlantic safety valve group, flange gasket, fittings).
• Dry the drip tray and leak sensor thoroughly. If the sensor remains triggered when dry, replace the leak sensor.
• Once all leaks are corrected and the sensor is dry, restore power and confirm that E40 clears.