Massey Ferguson 521005.11 – Engine Control Unit (ECU) / EEM4: NOx Sensor Before DOC Signal Issue

The engine management system has lost communication with the upstream Nitrogen Oxide (NOx) sensor, which is located in the exhaust stream before the Diesel Oxidation Catalyst (DOC). The FMI 11 designation specifically points to the sensor being 'missing' from the CAN bus network, meaning the controller is not receiving any valid signal or data from it.

• 7616
• 5612
• 7622
• Interim Tier 4 (2012-2015)
• 7614
• 5611
• 7615
• 5610
• 5613
• 7620
• 5609
• 7618
• 5608
• 7619
• 7626
• 7624
• MF 4707
• MF 4708
• MF 4709
• MF 4710
• MF 5608
• MF 5609
• MF 5610
• MF 5611
• MF 5612
• MF 5613
• MF 5710 SL
• MF 5711 SL
• MF 5712 SL
• MF 5713 SL
• MF 7614
• MF 7615
• MF 7616
• MF 7618
• MF 7619
• MF 7620
• MF 7622
• MF 7624
• MF 7626
• MF 7714 through 7726S

1. 1

   Check the electrical harness and the connector leading to the upstream NOx sensor (before the DOC) for melted wires, chafing, or corrosion.

2. 2

   Verify that the sensor is receiving proper supply voltage and ground, and check the auxiliary engine CAN connection to the NOx sensor.

3. 3

   Ensure there are no exhaust leaks prior to the DOC, which can skew readings or damage the sensor wiring.

4. 4

   Look for accompanying codes (like FMI 12 for stability time exceeded, or FMI 14 for supply voltage out of range) which might point to a broader electrical issue rather than a failed sensor.

1. 1

   Preparation

   Turn off the tractor, disconnect the battery, and allow the exhaust system to cool completely.

2. 2

   Removal

   Locate the upstream NOx sensor on the exhaust pipe before the DOC. Disconnect its electrical connector.

3. 3

   Extraction

   Carefully unscrew the sensor from the exhaust bung. Warning: Do not use an impact wrench for removal or installation, as this can damage the exhaust threads or the delicate sensor.

4. 4

   Cleaning

   Clean the exhaust pipe carbon deposits around the bung before installing the new sensor.

5. 5

   Installation

   Install the new NOx sensor. Warning: Do not touch the ceramic probe with bare fingers, as oil contamination will cause premature failure. Tighten to the manufacturer's specified torque.

6. 6

   Reconnection

   Plug in the electrical connector and reconnect the battery.

7. 7

   Clear Codes

   Turn the ignition on and use a diagnostic service tool to clear the E 521005.11 fault code from the ECU.