Electronic gas water heater displays E12; unit may short-cycle or fail to maintain temperature.

Safety: Disconnect power and allow plumbing to cool before servicing sensors.

• 1. Locate inlet sensor: On advanced American Water Heaters models, an inlet thermistor may be installed at the cold water inlet. Remove insulation to access.
• 2. Verify placement: Ensure the sensor is fully seated in its well or firmly attached to the inlet pipe with the provided clip and insulation.
• 3. Inspect wiring: Check for pinched or cut wires and reseat the connector at the control board.
• 4. Test resistance: Measure sensor resistance and compare to the temperature chart. Replace if readings are abnormal.
• 5. Replace control if needed: If wiring and sensor are good but E12 persists, the control board may be defective and should be replaced by a qualified technician.