New Holland ENG 3561 – Engine Control Module (ECM) / Electronic Diesel Control (EDC): NOx value not plausible (After treatment plausibility)

The Engine Control Module is receiving data from the Nitrogen Oxide (NOx) sensor that does not make logical sense given the current engine operating conditions. This plausibility failure typically means the NOx sensor itself has failed, or there is an underlying issue with the Selective Catalytic Reduction (SCR) system's efficiency (such as poor DEF quality or a failing catalyst) causing abnormal NOx emissions.

• New Holland T7 Series Tractors (e.g., T7.220, T7.235, T7.250, T7.260, T7.270)
• New Holland T8 Series Tractors
• New Holland CX Series Harvesters (e.g., CX8080, CX8090)
• New Holland Construction Equipment (e.g., L230 skid steers, telehandlers)

1. 1

   Scan for Associated Codes: Check if there are other active codes related to DEF/Urea quality (e.g., 3565, 3569) or SCR dosing. If DEF quality is poor, the NOx readings will naturally be implausible.

2. 2

   Inspect Wiring and Connections: Check the NOx sensor's wiring harness and CAN bus connector for corrosion, melting, or physical damage.

3. 3

   Check DEF Quality: Verify that the Diesel Exhaust Fluid is uncontaminated and at the correct concentration.

4. 4

   Inspect the Exhaust System: Look for exhaust leaks upstream of the NOx sensor, which can introduce unmetered oxygen and skew the sensor's readings.

1. 1

   Turn off machine and disconnect battery

   Turn off the machine, remove the key, and disconnect the battery to prevent electrical shorts.

2. 2

   Locate the faulty NOx sensor

   Locate the faulty NOx sensor on the exhaust aftertreatment system (typically mounted downstream of the SCR catalyst).

3. 3

   Disconnect electrical connector

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

4. 4

   Apply penetrating oil

   Apply penetrating oil to the sensor threads if the exhaust pipe is heavily rusted.

5. 5

   Remove the old NOx sensor

   Use a specialized sensor socket or wrench to carefully unscrew and remove the old NOx sensor.

6. 6

   Install the new NOx sensor

   Install the new NOx sensor into the exhaust pipe and tighten it to the manufacturer's specified torque.

7. 7

   Route wiring and reconnect plug

   Route the wiring away from extreme heat sources and reconnect the electrical plug.

8. 8

   Reconnect the battery

   Reconnect the battery.

9. 9

   Clear codes and perform resets

   Connect a diagnostic service tool to the machine, clear the ENG 3561 fault code, and perform any required SCR system resets or NOx sensor initialization procedures.