Massey Ferguson 3232.03 – Engine Control Unit (ECU): NOx Sensor Outlet SCR Signal Issue. (ECU)

This code indicates a signal or voltage irregularity (often a low voltage or abnormal update rate) from the NOx sensor located downstream of the Selective Catalytic Reduction (SCR) catalyst. The sensor is responsible for monitoring the nitrogen oxide levels in the exhaust after it has passed through the aftertreatment system to ensure the SCR system is functioning correctly.

• 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

   Check ECM Calibration: Verify that the engine ECM calibration is up to date. Outdated software can misinterpret sensor data and trigger false NOx codes.

2. 2

   Inspect Wiring and Connectors: Check the wiring harness leading to the NOx outlet sensor for breaks, chafing, corrosion, or shorts. Ensure the connector is properly seated and free of debris or moisture.

3. 3

   Test the CAN Network: Use a multimeter to check the J1939 Data Link (CAN lines) resistance at the sensor connector. It should read approximately 60 ohms.

4. 4

   Check for Exhaust Leaks: Inspect the exhaust system for blockages or leaks upstream of the sensor, which could skew the NOx readings.

5. 5

   Check Battery Voltage: Inspect the battery system. Low voltage or failing batteries can cause sensor communication dropouts.

6. 6

   Check for Accompanying Codes: Resolve any active codes related to the EGR, Turbo, or CAN communication lines before addressing the aftertreatment codes.

1. 1

   Cool Down

   Ensure the tractor is turned off and the exhaust system has completely cooled down to prevent severe burns.

2. 2

   Disconnect

   Locate the NOx Outlet Sensor (downstream of the SCR catalyst) and carefully unplug its electrical connector from the wiring harness.

3. 3

   Remove Sensor

   Use a specialized sensor socket or wrench to unscrew the NOx sensor from the exhaust pipe.

4. 4

   Prepare New Sensor

   Apply a small amount of high-temperature anti-seize compound to the threads of the new sensor (if not already pre-applied by the manufacturer). Be extremely careful not to get any anti-seize on the sensor probe itself.

5. 5

   Install

   Thread the new sensor into the exhaust pipe along with its sealing washer. Tighten to the manufacturer's specified torque.

6. 6

   Reconnect

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

7. 7

   Clear Codes

   Turn the key on and use an AGCO diagnostic tool (EDT) to clear the stored fault codes and reset the SCR/emissions system.