New Holland ENG 3841 – ENGINE ECU: Diesel Particulate Filter (DPF) Upstream Temperature Sensor: Diagnostic fault check for SRC low

The engine controller is receiving a voltage signal from the sensor that is below the minimum acceptable threshold, which typically points to a short circuit to ground in the wiring or an internal short within the sensor itself.

• L220
• L223
• L225
• L230
• C227
• C232
• C238
• W50C
• W60C
• W70C
• W80C
• W130C
• W170C
• W190C
• W230C
• W270C
• W300C
• T5.95
• T5.105
• T5.115
• CR6090
• CR7090
• CR8090
• CR9090
• CX8080
• CX8090

1. 1

   Inspect the wiring harness leading to the DPF upstream temperature sensor for any visible damage, chafing, or melting that could cause a short to ground.

2. 2

   Disconnect the sensor and check the connector pins for corrosion, moisture, or damage.

3. 3

   Use a multimeter to check the sensor's internal resistance. An out-of-spec reading or continuity to ground indicates a failed sensor.

4. 4

   Verify the reference voltage and ground supplied by the Engine ECU to the sensor connector. If the voltage is correct at the harness but drops when plugged in, the sensor is internally shorted.

1. 1

   Disconnect battery

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

2. 2

   Locate sensor

   Locate the DPF upstream temperature sensor. It is threaded into the exhaust pipe just before the Diesel Particulate Filter (DPF) / Diesel Oxidation Catalyst (DOC) assembly.

3. 3

   Disconnect electrical connector

   Disconnect the electrical connector for the sensor (often labeled X-476 or X-477 in CNH schematics).

4. 4

   Remove sensor

   Carefully unscrew the sensor from the exhaust pipe. Note: Exhaust sensors are prone to seizing due to extreme heat; applying penetrating oil and allowing it to soak beforehand is highly recommended.

5. 5

   Apply anti-seize

   Apply a small amount of high-temperature anti-seize compound to the threads of the new sensor (ensure no compound gets on the sensor probe itself).

6. 6

   Install new sensor

   Thread the new sensor into the exhaust pipe and tighten to the OEM torque specification.

7. 7

   Reconnect electrical connector

   Reconnect the electrical connector securely.

8. 8

   Reconnect battery

   Reconnect the battery.

9. 9

   Clear fault code

   Use a diagnostic tool (such as CNH EST) to clear the ENG 3841 fault code.

10. 10

    Verify repair

    Start the engine and monitor the exhaust temperature parameters to verify the new sensor is reading correctly. A forced DPF regeneration may be required to confirm full functionality under load.