Heater displays F09 and will not start; may be intermittent.

Safety first: Disconnect power before accessing sensors.

• Find outlet sensor: On models with dual sensors, the outlet sensor is mounted near the heater’s water outlet manifold.
• Check for moisture: Inspect the sensor and connector for signs of water intrusion or condensation. Dry the area thoroughly and correct any leaks above the sensor.
• Reseat connector: Unplug and replug the sensor connector at the control board to ensure a solid electrical connection.
• Replace if needed: If F09 persists, replace the outlet water temperature sensor following the same procedure as for the main water sensor.