ECU 000028.03 – Primary Analog Throttle Signal Out of Range High. John Deere Engine Control.

ECU 000028.03 (ECU 28.03)

Code: 000028.03

Shortcode: 28.03


The ECU 000028.03 (28.03) error code on John Deere equipment highlights an issue where the primary analog throttle signal exceeds the high voltage specifications expected by the foot throttle sensor. This could indicate a fault in the throttle sensor, wiring errors, or electronic noise influencing the signal. Such a high signal can result in unexpected engine acceleration, posing safety risks.


The engine control system may react by limiting engine output to prevent over-speed conditions and to maintain control over the vehicle’s operation.


  • Inspect Throttle Sensor and Circuitry: Check the throttle sensor and associated circuitry for any signs of damage or interference that could elevate signal voltage.
  • Diagnose with Precision Equipment: Utilize advanced diagnostic tools to isolate the cause of the high signal, checking for electrical interference or sensor faults.
  • Replace Affected Components: Replace the throttle sensor or any associated components if they are found to be defective.
  • Reset and Verify System Operation: After component replacement, reset the error codes and test the throttle system across all operational parameters to ensure stable and accurate response.


Maintaining the throttle control system in optimal condition is critical for safe and efficient operation of John Deere machinery. Regular diagnostics and maintenance can preemptively address issues that might lead to error codes such as ECU 000028.01 and ECU 000028.03, thereby avoiding potential safety hazards and operational inefficiencies. Regular firmware updates and calibration are also advisable to keep the system’s performance aligned with engine requirements.

Control Units: John Deere

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