ECU 000028.04 – Primary Analog Throttle Signal Out of Range Low. John Deere Engine Control.

ECU 000028.04 (ECU 28.04)

Code: 000028.04

Shortcode: 28.04


The ECU 000028.04 (28.04) error code indicates that the primary analog throttle signal on John Deere machinery is below the low voltage specifications set for the foot throttle sensor. This situation usually occurs due to issues such as a faulty throttle sensor, poor electrical connections, or a broken wire that can lead to a drop in voltage. Low throttle signals can cause reduced engine response or failure to respond to throttle inputs, directly impacting the vehicle’s performance and handling.


The John Deere engine control system may initiate a reduced power mode or engage safety protocols to limit vehicle operation, ensuring both operator safety and engine protection.


  • Inspect Throttle Sensor and Electrical Connections: Check the throttle sensor and all associated electrical connections for corrosion, breaks, or loose contacts that might contribute to low voltage readings.
  • Test Throttle Sensor Output: Utilize diagnostic tools to measure the output from the throttle sensor. Ensure it aligns with expected parameters for various throttle positions.
  • Repair or Replace Faulty Components: If the throttle sensor or any part of its circuitry is damaged, replace these with original John Deere components to guarantee system integrity and performance.
  • System Reset and Thorough Testing: After repairs, clear any fault codes and conduct comprehensive testing to verify that the throttle operates correctly and consistently under all conditions.


Regular preventative maintenance and timely repairs of the throttle system are essential to avoid operational issues and ensure that John Deere vehicles operate efficiently and safely. Regular checks for wiring integrity and sensor functionality can prevent many common throttle-related problems. Additionally, keeping the engine and its control software up to date can help prevent these issues by ensuring all components communicate correctly and function as intended.

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