Case IH 19063 (DTC 4A8E) - ECU – Engine Control Unit (ECU) / Engine Management System (EMS): Upstream NOx sensor supply voltage is out of range.

The Engine Control Unit (ECU) has detected that the electrical supply voltage feeding the upstream NOx sensor is either too high, too low, or erratic compared to the expected operating parameters.

• MAXXUM T4E
• 240 Series Axial-Flow Combines (7240, 8240, 9240)
• Magnum series (180 through 370)
• Steiger / Quadtrac series (350 through 600)
• Puma series
• Titan Floaters (3030, 3530, 4030, 4530)

1. 1

   Inspect the wiring harness leading to the upstream NOx sensor for melted wires, chafing, or breaks in the insulation.

2. 2

   Disconnect the sensor (5-pin MCON connector) and inspect the pins for corrosion, moisture intrusion, or bent terminals.

3. 3

   Turn the key to the ON position and measure the supply voltage and ground at the harness side of the connector to ensure it matches system specification (12V or 24V) and is stable.

4. 4

   Look for other active codes (such as CAN bus communication timeouts or general SCR power supply faults) which may indicate a shared fuse, relay, or ECU issue.

1. 1

   Turn off the machine, remove the key, and disconnect the battery to prevent electrical shorts.

   Ensure the machine is completely powered down before beginning work.

2. 2

   Locate the upstream NOx sensor on the exhaust pipe, situated between the engine turbo outlet and the DOC/SCR canister.

   Identify the correct sensor location.

3. 3

   Disconnect the electrical connector from the NOx sensor control module.

   Carefully unplug the module.

4. 4

   Using an appropriate sensor socket or wrench, carefully unscrew the NOx sensor probe from the exhaust pipe.

   Note: Penetrating oil may be required if the sensor is seized from exhaust heat.

5. 5

   Apply a small amount of high-temp anti-seize compound to the threads of the new NOx sensor.

   Be extremely careful not to get any anti-seize on the sensor tip.

6. 6

   Thread the new upstream NOx sensor into the exhaust pipe and tighten to the manufacturer's specified torque.

   Ensure the sensor is properly seated and torqued.

7. 7

   Mount the sensor's control module, route the wiring away from extreme heat sources, and plug in the electrical connector.

   Secure the wiring to prevent future heat damage.

8. 8

   Reconnect the battery.

   Restore power to the machine.

9. 9

   Connect a diagnostic tool (such as the Case IH Electronic Service Tool) to clear the fault code (19063 / 4A8E).

   Clear the inactive codes from the ECU.

10. 10

    Start the engine and allow it to reach operating temperature to verify the code does not return and the SCR system is functioning normally.

    Confirm the repair was successful.