Case IH 3526 (DTC E28E) - ECU – Engine Control Unit (ECU) / Electronic Diesel Control (EDC): Downstream NOx sensor internal failure (Short Circuit Error)

This code indicates that the system has detected a short circuit within the downstream Nitrogen Oxide (NOx) sensor or its immediate circuit, which monitors the exhaust gases after they pass through the Selective Catalytic Reduction (SCR) catalyst.

• MAXXUM T4E
• Axial-Flow Combines 240 Series (7240, 8240, 9240)
• Farmall Tractors 110A
• Farmall Tractors 120A
• Farmall Tractors 130A
• Farmall Tractors 140A
• Farmall Tractors 40-45-50 series
• Magnum Tractors 180
• Magnum Tractors 335
• Magnum Tractors Pro series

1. 1

   Inspect the wiring harness leading to the downstream NOx sensor for any visible chafing, melting, or pinched wires that could cause a short circuit to ground or battery voltage

2. 2

   Disconnect the NOx sensor and inspect the pins inside the connector for corrosion, moisture, or bent pins that could bridge the connections

3. 3

   Verify that the sensor is receiving the correct power supply and that the ground circuit is intact

4. 4

   Check the fuses related to the SCR dosing system and NOx sensors to ensure a short hasn't blown the circuit protection

1. 1

   Power Down

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

2. 2

   Locate the Sensor

   Locate the downstream NOx sensor on the exhaust pipe (positioned after the SCR catalyst).

3. 3

   Disconnect

   Unplug the electrical connector from the NOx sensor module.

4. 4

   Remove

   Use a specialized NOx sensor socket or wrench to carefully unscrew the sensor from the exhaust bung. (Penetrating oil may be required if the sensor is seized from exhaust heat).

5. 5

   Install

   Thread the new downstream NOx sensor into the exhaust bung and tighten it to the manufacturer's torque specification.

6. 6

   Reconnect

   Plug the sensor's electrical connector back into the machine's wiring harness.

7. 7

   Clear Codes

   Reconnect the battery, use a diagnostic service tool to clear the inactive 3526 / E28E fault code, and run the engine to verify that the code does not return.