Massey Ferguson E521004.11 – Engine Control Unit (ECU) / EEM4: Downstream NOx Sensor Missing

The Engine Electronic Management (EEM4) monitoring system cannot detect the downstream NOx sensor on the vehicle's CAN bus network.

• 7616
• 5612
• 7622
• Interim Tier 4 (2012-2015)
• 7614
• 5611
• 7615
• 5610
• 5613
• 7620
• 5609
• 7618
• 5608
• 7619
• 7626
• 7624
• 4607M
• 4609M
• 4707
• 4708
• 4709
• 4710
• 5709
• 5710
• 5711
• 5712
• 5713
• 6612
• 6613
• 6614
• 6615
• 6616
• 6712S
• 6713S
• 6714S
• 6715S
• 6716S
• 6718S
• 7714-7726
• 8650
• 8660
• 8670
• 8680
• 8690
• 8727
• 8730
• 8732
• 8735
• 8737
• 8740
• 7345
• 7347
• 9540
• 9560
• IDEAL 7

1. 1

   Inspect the NOx sensor wiring harness for chafing, melting, or breaks, as it is routed near the high-heat exhaust/SCR system.

2. 2

   Disconnect the downstream NOx sensor and inspect the pins for water ingress, corrosion, or backed-out terminals.

3. 3

   Verify that the sensor is receiving proper power (+15V supply) and a solid ground at the connector.

4. 4

   Test the CAN High and CAN Low pins at the connector for proper voltage and continuity back to the ECU.

5. 5

   If multiple CAN bus fault codes are present, check the main harness or CAN resistor, as the issue is likely network-related rather than the sensor itself.

1. 1

   Disconnect battery

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

2. 2

   Locate sensor

   Locate the downstream NOx sensor on the SCR/exhaust pipe assembly.

3. 3

   Disconnect electrical connector

   Disconnect the electrical connector from the sensor module.

4. 4

   Remove sensor probe

   Carefully unscrew the NOx sensor probe from the exhaust pipe. (Tip: Exhaust sensors frequently seize; apply penetrating oil and allow it to soak if resistance is high to avoid stripping the exhaust bung threads).

5. 5

   Install new sensor

   Install the new NOx sensor probe and tighten it to the manufacturer's specified torque.

6. 6

   Mount module and reconnect

   Mount the sensor's control module and reconnect the electrical connector. Ensure the wiring is secured away from direct contact with the exhaust pipe.

7. 7

   Reconnect battery

   Reconnect the battery and turn on the ignition.

8. 8

   Clear codes and verify

   Connect a diagnostic service tool to the tractor, clear the EEM4 fault codes, and run the engine to verify the code does not return.