Case IH 19178 (F-3234-14) - ECU – Engine Control Unit (ECU): Downstream NOx sensor has too often aborted its self-diagnosis check during afterrun

A calibration or software issue where the self-diagnostic request is being sent to the smart NOx sensor too early after the engine stops, or the sensor's internal software is too old to perform the self-diagnostic check properly.

• VESTRUM CVX
• Austoft 9900
• Magnum
• Steiger
• Puma
• 621G
• 721G
• 821G
• 1021G

1. 1

   Verify the software version of the downstream NOx sensor using a diagnostic tool, as older sensor types cannot perform this self-diagnostic.

2. 2

   Check for accompanying NOx sensor codes (e.g., 3234-12, 3234-16, 3234-18) which might indicate physical connection issues, plausibility errors, or CAN controller faults.

3. 3

   Inspect the physical presence, correct connection, and wiring of the downstream NOx sensor to the CAN network to rule out a communication drop-off during the afterrun cycle.

1. 1

   Connect diagnostic tool

   Connect the diagnostic tool and confirm the presence of code 19178 (F-3234-14).

2. 2

   Locate sensor

   Locate the downstream NOx sensor. It is located directly after the Selective Catalytic Reduction (SCR) catalyst.

3. 3

   Disconnect sensor

   Disconnect the sensor from the machine's wiring harness.

4. 4

   Replace sensor

   Replace the sensor with an updated and compatible version because the old sensor software cannot be updated to handle the self-diagnostic timing.

5. 5

   Install new sensor

   Install the new, updated downstream NOx sensor and torque to OEM specifications.

6. 6

   Reconnect wiring

   Reconnect the wiring harness.

7. 7

   Clear fault codes

   Clear the fault codes using the diagnostic tool.

8. 8

   Verify repair

   Run the engine up to operating temperature and shut it down to allow the system to perform a complete afterrun cycle. Verify the self-diagnosis completes successfully and the code does not return.