John Deere 5128.06 – ECU: Sensor Supply Voltage 10, Resistance Too Low

This diagnostic trouble code indicates that the resistance in the 12V supply voltage circuit for 'Sensor 10' is too low. This condition typically means there is a short to ground in the wiring harness or within a connected component, causing a higher-than-expected current (high amp flow) when the driver is active.

• 5085E
• 5090E
• 5090EL
• 5100E
• 5090M
• 5100M
• 5100MH
• 5100ML
• 5115M
• 7R Series (7210R–7310R)
• 8R Series (8245R–8400R)
• 9RT Series (9470RT, 9520RT, 9570RT)
• 544K Wheel Loaders
• R4030
• R4038
• R4045

1. 1

   Inspect the aftertreatment wiring harness leading to the NOx sensors for damaged, frayed, or melted wires, especially near hot exhaust components or sharp chassis edges.

2. 2

   Isolate the short circuit to determine if it is located inside a NOx sensor or within the wiring harness.

3. 3

   Verify the electrical supply to ensure the ECU is outputting the correct voltage to the circuit when the sensors are unplugged.

1. 1

   Verify active code

   Turn the key to the ON position (engine OFF) and verify that code 005128.06 is active.

2. 2

   Disconnect outlet sensor

   Disconnect the Aftertreatment Outlet NOx Sensor. Check if the fault code changes from active to inactive (or changes to an open circuit/communication code).

3. 3

   Disconnect inlet sensor

   Disconnect the Aftertreatment Inlet NOx Sensor and observe the code status again.

4. 4

   Evaluate sensors

   If unplugging one of the NOx sensors causes the 5128.06 'Resistance Too Low' code to clear, that specific NOx sensor has an internal short and must be replaced.

5. 5

   Evaluate harness

   If the code remains active even with both NOx sensors unplugged, the short to ground is located within the wiring harness itself. Trace the Sensor Supply #10 wire back to the ECU, locate the rubbed/shorted section, and repair or insulate the wire.

6. 6

   Reset and monitor

   Once the sensor is replaced or the wire is repaired, clear the ECU fault codes and run the engine to ensure the code does not return and the aftertreatment system functions normally.