ATC 524203.04 – B125 Sensor for Ambient Air Temperature (Front), Voltage Too Low. John Deere System Advisory.

ATC 524203.04 (ATC )

Code: 524203.04



The error code, ATC 524203.04, is triggered when the control unit measures 0 volts at the signal input for the front ambient air temperature sensor (B125, lead 2001). This absence of voltage typically indicates a short to ground in the circuit, which can prevent the sensor from functioning and delivering accurate temperature readings.


The low voltage condition may cause the HVAC system to receive no data from the ambient air temperature sensor, potentially causing the system to operate based on default settings or erroneous data, which could affect climate control effectiveness and comfort inside the cabin.


  • Inspect Wiring and Connections: Examine the wiring and connections at lead 2001 for signs of damage, corrosion, or grounding issues that could create a short.
  • Measure and Diagnose the Circuit: Use a multimeter to check for continuity and to identify where the short to ground is occurring within the circuit.
  • Repair or Replace Faulty Wiring or Components: Once the source of the short is identified, repair the damaged wires or replace faulty components to restore proper circuit functionality.
  • Test Sensor Functionality: After repairs are made, test the ambient air temperature sensor to ensure it functions correctly and provides accurate temperature readings.
  • Reset System and Perform Functional Testing: Clear any fault codes from the system and conduct a full operational test to ensure that all components function correctly and that the issue has been fully resolved.


Regular maintenance and timely inspection of electrical systems, especially those related to sensors and data inputs, are crucial for ensuring reliable operation. Promptly addressing electrical faults such as shorts to ground helps maintain the effectiveness of the HVAC system and ensures that vehicle occupants enjoy a comfortable and controlled environment.