John Deere 51.03 – Engine Control Unit (ECU): Air Throttle Actuator Position Signal Out of Range High

This code indicates that the position signal from the air throttle actuator is exceeding the expected high range. This is typically caused by a short to a 12-volt source, damaged wiring insulation, or an internal electrical fault within the throttle actuator itself. When this code is active, the engine will limit power (derate), and Active Exhaust Filter cleaning (regeneration) will be unavailable.

• 5085E
• 5090E
• 5090EL
• 5100E
• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 8245R
• 8400R
• 8310RT
• 8360RT
• 204L
• 304L
• 85G
• 7400A
• 4TNV98C
• 4TNV98CT

1. 1

   Read and verify codes using John Deere Service ADVISOR to confirm 000051.03 is active and check for related codes (like 000051.14).

2. 2

   Inspect the air throttle actuator wiring harness and electrical connectors for signs of wear, abrasion, corrosion, or pin damage, especially where wires may contact metal parts.

3. 3

   Perform a continuity and voltage test using a multimeter to test the actuator circuitry for a short to high voltage.

4. 4

   Test actuator operation via Service ADVISOR. Listen for smooth movement; sticking or grinding indicates a failing actuator motor.

5. 5

   Inspect the intake throttle plate for heavy carbon buildup that could cause the valve to stick and throw the position sensor out of range.

1. 1

   Disconnect Power

   Turn off the machine and disconnect the battery to prevent electrical spikes during repair.

2. 2

   Repair Wiring

   If the diagnostic checks revealed damaged insulation or a short to 12V in the harness, repair the wiring or replace the affected harness section.

3. 3

   Replace the Actuator

   If the wiring is intact but the actuator fails the Service ADVISOR test or has an internal short, remove the defective air throttle valve assembly.

4. 4

   Clean the Mating Surface

   Remove any old gasket material from the intake manifold connection.

5. 5

   Install the New Valve

   Install the replacement air throttle valve with a new gasket. Torque the mounting bolts to OEM specifications.

6. 6

   Reconnect and Calibrate

   Reconnect the electrical harness. Reconnect the battery.

7. 7

   Clear Codes and Test

   Use the diagnostic tool to clear the 000051.03 fault code. Run the engine and conduct a comprehensive test (or an actuator calibration learn procedure if required by the specific engine manual) to ensure the actuator operates within the correct parameters and the code does not return.