John Deere 5128.05 – ECU: Sensor Supply Voltage 10, Resistance Too High

The code specifically indicates an open circuit (resistance too high) on the 12V Sensor Supply #10 circuit, which provides power to the Aftertreatment Outlet NOx Sensor and related aftertreatment components.

• 5085E
• 5090E
• 5090EL
• 5100E
• 5090M
• 5100M
• 5100MH
• 5100ML
• 5115M
• 4.5L (4045) PowerTech Engine
• 6.8L OEM Diesel Engine
• 8245R
• 8270R
• 8295R
• 8320R
• 8335R
• 8345R
• 8370R
• 8400R
• 9470RT
• 9520RT
• 9570RT
• 7210R
• 7230R
• 7250R
• 7270R
• 7290R
• 7310R

1. 1

   Visually inspect the wiring harness and connectors associated with Sensor Supply #10 (specifically routing to the Aftertreatment Outlet NOx Sensor) for damaged, frayed, or loose connections.

2. 2

   Use a multimeter or diagnostic tool to test the NOx sensor for proper resistance and continuity.

3. 3

   Ensure that the 12V electrical supply from the ECU to the sensor is stable and within specifications.

4. 4

   Check for open circuits by focusing on finding broken wires, corroded pins, or disconnected plugs rather than shorts to ground.

1. 1

   Isolate the Circuit

   Disconnect the battery or turn the machine off to safely work on the engine wiring harness.

2. 2

   Repair Wiring

   If the diagnostic checks reveal a broken wire or corroded connector on the Sensor Supply #10 circuit, repair the wiring or replace the damaged connector pigtail.

3. 3

   Replace the Sensor

   If the wiring is intact but the NOx sensor itself has an internal open circuit (fails the continuity test), remove and replace the Aftertreatment Outlet NOx Sensor.

4. 4

   Reset and Monitor

   Reconnect all components, turn the machine on, and use a diagnostic tool (such as John Deere Service ADVISOR) to reset the ECU and clear the fault code. Run the engine and monitor the system to ensure the code does not return and the aftertreatment system operates normally.