Massey Ferguson 3219.02 – Engine Control Unit (ECU): NOx Sensor Before DOC Signal Issue

The nitrogen oxide (NOx) sensor located upstream (before) the Diesel Oxidation Catalyst (DOC) is sending an invalid, missing, or out-of-range signal to the engine control system. This sensor is critical for measuring the NOx levels in the raw exhaust gases before they enter the aftertreatment system, which allows the system to calculate the correct amount of AdBlue/DEF to inject.

• 4710
• 7724S
• 5712SL
• 7722S
• 7722
• 5713SL
• 7720S
• 7716
• 7718
• T4
• 7715
• 5710SL
• 7726
• 4708
• 7726S
• 4707
• 4709
• 5711SL
• 7718S
• 7719
• 7714
• 7716S
• T4 (2015-2021)
• 7720
• Tier 4 (2015-2021)
• 7715S
• 7724
• 5608
• 5609
• 5610
• 5611
• 5612
• 5613
• 7614
• 7615
• 7616
• 7618
• 7619
• 7620
• 7622
• 7624
• 7626

1. 1

   Visually inspect exhaust piping and joints before the DOC for leaks, as fresh air entering or exhaust escaping can skew NOx readings.

2. 2

   Inspect the upstream NOx sensor wiring harness and connector for chafing, heat damage, corrosion, or loose connections on the auxiliary engine CAN bus circuit.

3. 3

   Use a diagnostic tool (like Massey Ferguson EDT) to monitor live data from the NOx sensor before the DOC, checking for impossible values or missing CAN bus communication.

1. 1

   Turn off tractor and disconnect battery

   Turn off the tractor and disconnect the battery to ensure safety while working on the electrical and exhaust systems.

2. 2

   Locate NOx sensor

   Locate the NOx sensor upstream of the DOC (Diesel Oxidation Catalyst) in the exhaust stream.

3. 3

   Disconnect electrical connector

   Disconnect the sensor's electrical connector from the engine wiring harness.

4. 4

   Unscrew NOx sensor

   Carefully unscrew the NOx sensor from the exhaust pipe. (Note: Penetrating oil may be required if the sensor threads are seized due to high exhaust heat).

5. 5

   Install new NOx sensor

   Install the new genuine OEM NOx sensor. Ensure it is tightened to the manufacturer's specified torque.

6. 6

   Reconnect electrical connector

   Reconnect the electrical connector. Crucial step: Route the NOx sensor harness exactly as it was from the factory to prevent future failures from heat soak or vibration.

7. 7

   Reconnect battery

   Reconnect the battery.

8. 8

   Clear fault code and verify

   Connect the EDT diagnostic tool, clear the active 003219.02 fault code, and run the engine to operating temperature (above 200°C / 392°F) to verify that the sensor is reading correctly and the code does not return.