ATC 524203.03 – B125 Sensor for Ambient Air Temperature (at Front), Voltage Too High. John Deere System Advisory.

ATC 524203.03 (ATC )

Code: 524203.03



The error code, ATC 524203.03, is triggered when the control unit measures a voltage exceeding 5 volts at the signal input for the front ambient air temperature sensor (B125, lead 2001). This high voltage typically indicates that the circuit is either shorted to a supply lead or is open. Such an electrical fault can lead to incorrect temperature readings being reported by the sensor.


The faulty voltage readings may cause the HVAC system to receive incorrect ambient temperature data, potentially leading to inappropriate climate control settings and reduced comfort or efficiency within the cabin.


  • Inspect Wiring and Connections: Check the wiring and connections at lead 2001 for any signs of damage, wear, or improper connections that might lead to a short to power supply or an open circuit.
  • Measure Voltage Levels: Use a multimeter to verify the voltage at the sensor’s signal input. High readings confirm the presence of an electrical fault.
  • Identify and Repair Circuit Issues: Locate and repair any shorts to power or open connections within the circuit. Replace damaged wires or connectors as necessary.
  • Test Sensor Functionality: After repairs, test the ambient air temperature sensor to ensure it accurately measures and reports temperatures.
  • Reset System and Verify Operation: Clear any stored fault codes and perform a comprehensive test to ensure the temperature sensor and HVAC system operate correctly under normal conditions.


Maintaining the integrity of sensor circuits within the HVAC system is crucial for ensuring accurate environmental control. Regular maintenance and inspection of these sensors and their wiring can prevent issues that lead to incorrect temperature control and ensure the comfort and safety of vehicle occupants. Addressing voltage irregularities promptly helps maintain the performance and reliability of the climate control systems.