Massey Ferguson 3232.05 – ECU: NOx Sensor Outlet SCR Signal Issue. (ECU)

This code indicates a signal fault with the downstream Nitrogen Oxide (NOx) sensor, which is located at the outlet of the Selective Catalytic Reduction (SCR) catalyst. The ".05" failure mode identifier (FMI) typically points to an electrical issue, such as an open circuit, high resistance, or an implausible signal being returned to the controller. This means the computer cannot accurately verify if the AdBlue/DEF system is successfully reducing emissions.

• 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
• 5709
• 6711
• 6712
• 6714S
• 6715S
• 6716S
• 6718S
• 7614
• 7615
• 7616
• 7618
• 7619
• 7620
• 7622
• 7624
• 7626
• 7714S
• 7719S

1. 1

   Inspect the wiring harness and connector leading to the Outlet NOx sensor for melted wires, chafing, or corrosion in the pins.

2. 2

   Inspect the exhaust pipe between the SCR catalyst and the NOx sensor for leaks that can introduce oxygen and skew readings.

3. 3

   Use a multimeter to verify the sensor is receiving proper supply voltage and ground, and check CAN bus communication lines for continuity back to the ECU.

4. 4

   Test the resistance across the sensor's pins to check for an open circuit (infinite resistance) or out-of-spec readings indicating internal failure.

5. 5

   Ensure the DEF tank is full and the dosing injector is not clogged, as a failed dosing event can cause the ECU to flag the sensor signal as implausible.

1. 1

   Preparation

   Park the tractor on a level surface, turn off the engine, and remove the key. Crucial: Allow the exhaust system to cool completely, as the SCR and DPF components operate at extremely high temperatures.

2. 2

   Locate the Sensor

   Find the Outlet NOx sensor. It is threaded into the exhaust tailpipe downstream of the SCR catalyst canister. Do not confuse it with the Inlet NOx sensor (which is upstream of the SCR).

3. 3

   Disconnect Wiring

   Unplug the electrical connector for the NOx sensor from the main engine wiring harness.

4. 4

   Remove the Sensor

   Use a specialized NOx sensor socket or a wrench to unthread the sensor from the exhaust pipe. If the sensor is seized due to heat cycling, apply penetrating oil to the threads and allow it to soak before attempting removal.

5. 5

   Install the New Sensor

   Apply a small amount of high-temperature anti-seize compound to the threads of the new sensor (if it does not come pre-applied). Thread the sensor into the exhaust pipe by hand to prevent cross-threading, then tighten to the OEM torque specification.

6. 6

   Reconnect

   Plug the new sensor's electrical connector back into the wiring harness, ensuring the locking tab clicks into place. Secure any loose wiring with zip ties away from hot exhaust components.

7. 7

   Clear Codes

   Connect an AGCO Electronic Diagnostic Tool (EDT) or a compatible heavy-duty scanner to the tractor. Clear the 003232.05 fault code from the ECU.

8. 8

   Validation

   Start the tractor and allow it to reach operating temperature. Monitor the live data for the Outlet NOx sensor to ensure it is reading correctly and that the tractor exits any derate modes.