A09
Beretta Return Temperature NTC Sensor Fault

A09 displayed; heater may overheat or not regulate temperature correctly

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Failed return NTC sensor, Poor sensor contact with pipe, Wiring harness fault, Control board sensor circuit failure

How to Fix / Troubleshooting

Safety: Turn off power and allow the unit to cool before working on sensors.

  • 1. Reset and monitor: Reset the heater and observe operation. If A09 reappears, the return sensor is likely faulty.
  • 2. Locate return NTC: This sensor is usually on the return pipe entering the heat exchanger.
  • 3. Check physical condition: Ensure the sensor is firmly attached and not corroded or wet from leaks.
  • 4. Test sensor (technician): Measure resistance and compare with Beretta's NTC chart. Replace if out of tolerance.
  • 5. Wiring and PCB check: If sensor tests good, a technician should check wiring continuity and the PCB input.
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Repair Difficulty

Medium 3/5

Required Part

Return NTC sensor
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