Display shows A19; water heater indicates sensor fault on cold water inlet or mixing valve sensor (if equipped).

Safety first: Disconnect power before working on sensors or control wiring.

This alarm relates to the sensor used to monitor cold inlet or mixing valve temperature.

• Step 1 – Locate sensor:
  • Identify the sensor on the cold inlet pipe or mixing valve body.
• Step 2 – Check attachment and insulation:
  • Ensure good thermal contact and re-insulate the sensor area.
• Step 3 – Inspect wiring and test:
  • Check for cable damage and reseat connectors.
  • Measure resistance and compare to expected values.
• Step 4 – Reset alarm:
  • Restore power, clear the alarm, and verify stable readings.

Replace the sensor if faulty; if mapping is wrong, correct the configuration in the installer menu.