New Holland ENG 3981 – Engine ECU: Diesel Oxidation Catalyst (DOC) IN Temperature under 220 °C (428 °F) during regeneration

The Diesel Oxidation Catalyst (DOC) is the first section of the aftertreatment assembly, responsible for utilizing a chemical process to break down pollutants. For a successful exhaust regeneration to occur, the exhaust gas entering the DOC must reach a minimum operational temperature threshold. This fault code triggers when the system detects that the exhaust gas temperature at the DOC inlet has failed to reach 220 °C (428 °F) while an active regeneration cycle is being attempted.

• L220
• SR160
• SR175
• SV185

1. 1

   Use a diagnostic scan tool to monitor the live data of the DOC Inlet Temperature Sensor (EGTS). Verify if the temperature reading is plausible (e.g., it should match ambient temperature when the engine is completely cold).

2. 2

   Inspect the wiring harness and connectors for the DOC inlet temperature sensor for chafing, corrosion, or loose pins.

3. 3

   Check for exhaust leaks between the engine exhaust manifold, turbocharger, and the DOC inlet. A leak can cause a loss of exhaust heat before it reaches the sensor.

4. 4

   If the sensor is reading accurately, check for concurrent fault codes regarding the intake throttle, EGR system, or fuel injectors. These systems are responsible for elevating exhaust temperatures, and failures here can prevent the engine from generating enough heat.

1. 1

   Turn off the machine and allow the exhaust system to cool completely.

   This is necessary to avoid severe burns.

2. 2

   Locate the DOC Inlet Temperature Sensor (EGTS).

   It is mounted in the exhaust pipe just before the Diesel Oxidation Catalyst.

3. 3

   Disconnect the sensor's electrical connector and inspect for any signs of moisture or damage.

4. 4

   Remove the faulty sensor using the appropriate wrench.

   If the sensor is determined to be faulty (reading out of range or physically damaged), apply penetrating oil if the sensor is seized in the exhaust bung to prevent stripping the threads.

5. 5

   Install the new Exhaust Gas Temperature Sensor.

   Apply a high-temp anti-seize compound to the threads (if not pre-applied) and torque to the manufacturer's specification.

6. 6

   Reconnect the electrical harness.

7. 7

   Clear the fault codes using a diagnostic scan tool.

8. 8

   Initiate a forced stationary regeneration using the scan tool.

   Verify that the DOC inlet temperature now successfully rises above 220 °C (428 °F) and completes the cycle.