Massey Ferguson 3216.19 – ECU: NOx Sensor Before DOC Signal Missing.

The Engine Control Unit (ECU) has lost communication with the upstream Nitrogen Oxide (NOx) sensor located before the Diesel Oxidation Catalyst (DOC) in the exhaust aftertreatment system. The ECU is not receiving the expected data signal from the sensor via the CAN bus network.

• 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

   Locate the NOx sensor upstream of the DOC. Inspect the sensor body, wiring pigtail, and the main harness connector for physical damage, melting from exhaust heat, or chafing.

2. 2

   Disconnect the NOx sensor and inspect the pins for corrosion, moisture, or pushed-out terminals.

3. 3

   Verify that the sensor is receiving proper supply voltage and has a solid ground.

4. 4

   Check the CAN High and CAN Low lines between the NOx sensor connector and the ECU for continuity and proper resistance.

1. 1

   Preparation

   Turn off the tractor, remove the key, and disconnect the battery to prevent electrical spikes. Ensure the exhaust system has completely cooled down.

2. 2

   Removal

   Disconnect the electrical connector for the upstream NOx sensor. Unclip the sensor's wiring harness from any retaining brackets. Using a specialized NOx/O2 sensor socket or a suitable wrench, carefully unscrew the sensor from the exhaust pipe before the DOC. (Penetrating oil may be required if the threads are seized).

3. 3

   Installation

   Apply a small amount of anti-seize compound to the threads of the new sensor (if not already pre-applied by the manufacturer). Do not get anti-seize on the sensor tip. Thread the new sensor into the exhaust pipe by hand to prevent cross-threading, then tighten to the OEM torque specification. Route the wiring harness exactly as it was originally, securing it away from extreme heat sources. Reconnect the electrical connector.

4. 4

   Validation

   Reconnect the battery. Connect a diagnostic service tool (such as AGCO EDT) to clear the inactive fault codes. Start the engine and allow it to reach operating temperature to verify the ECU is receiving the NOx signal and the code does not return.