ATC 524219.02 – B143 Defog Sensor, Frequency Out of Valid Range. John Deere System Advisory.

ATC 524219.02 (ATC )

Code: 524219.02



The error code, ATC 524219.02, is triggered when the control unit detects that the frequency from the defog sensor (B143, lead 2003) is outside the valid frequency range (32.26 – 37.88 Hz). Deviations from the specified frequency range can indicate a malfunction within the sensor or associated circuitry, affecting its ability to accurately detect fogging conditions on the vehicle’s windows.


This fault may lead to improper activation or non-activation of the defogging system, potentially compromising visibility and safety during conditions where window defogging is necessary.


  • Inspect Sensor and Wiring: Check the defog sensor and its wiring for signs of damage, corrosion, or loose connections that might affect frequency readings.
  • Measure Sensor Frequency: Use appropriate diagnostic tools to measure the frequency output of the defog sensor to verify if it falls within the specified range.
  • Replace or Repair Faulty Sensor: If the sensor is found to be producing incorrect frequencies consistently, consider replacing it or repairing any issues in its circuitry.
  • Test System Functionality: After any repairs or replacements, test the defog system to ensure it activates correctly based on the sensor’s readings.
  • Reset Fault Codes and Recheck the System: Clear any fault codes from the system and perform a complete check to ensure no further issues are present and that the sensor is functioning within its normal operational range.


Regular checks and maintenance of environmental sensors like the defog sensor are critical for ensuring they function effectively and reliably. These sensors play a crucial role in maintaining clear visibility and safe driving conditions, making their proper operation fundamental to vehicle safety and comfort. Addressing issues promptly helps maintain system reliability and prevent visibility-related hazards.