ATC 524219.03 – B143 Defog Sensor, Voltage Too High. John Deere System Advisory.

ATC 524219.03 (ATC )

Code: 524219.03



The error code, ATC 524219.03, is triggered when the control unit detects that the voltage at the signal input for the defog sensor (B143, lead 2003) is too high, indicating that the circuit may be shorted to a supply lead or is open. This abnormal voltage can affect the sensor’s ability to accurately detect fogging on the vehicle’s windows, leading to potential failures in the defogging system.


The high voltage condition may prevent the defog sensor from operating correctly, potentially resulting in the defogging system failing to activate when needed, which can compromise visibility and safety.


  • Inspect Sensor Wiring and Connections: Check the wiring and connections at lead 2003 for any signs of damage, corrosion, or improper connections that might lead to a voltage anomaly.
  • Measure Voltage Levels: Use a multimeter to verify the voltage at the defog sensor’s signal input. Compare it against the normal operating specifications to determine if it is indeed too high.
  • 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 making electrical repairs, test the defog sensor to ensure it functions correctly and provides accurate readings.
  • Reset System and Verify Operation: Clear any stored fault codes and perform a comprehensive test to ensure the defog system operates correctly under normal conditions.


Maintaining the electrical integrity of sensors within the HVAC system is crucial for ensuring consistent and reliable operation. Regular checks and timely repairs of electrical issues are critical to avoid operational disruptions and maintain cabin comfort. Addressing voltage irregularities promptly helps maintain the effectiveness of the climate control system and ensures the safety and comfort of vehicle occupants.