Case IH 3887 – Engine Control Unit (ECU): DOC Intake Temperature Higher Than 700 deg C

Exhaust gas temperature entering the Diesel Oxidation Catalyst has exceeded safe operating limits. This over-temperature condition is typically caused by a failing temperature sensor reading incorrectly, or an uncontrolled exothermic reaction (heat spike) in the exhaust caused by excessive unburnt fuel entering the DOC (usually due to leaking fuel injectors or a faulty hydrocarbon doser).

• skid steer
• SR175
• SR210B
• SR240
• SV280B
• TR270B
• TR310
• TV370B
• Steiger
• Magnum
• Puma

1. 1

   Verify Sensor Accuracy: Use a diagnostic tool to monitor the DOC intake temperature sensor when the engine is completely cold. The reading should match the ambient air temperature. If it reads artificially high, the sensor is likely faulty.

2. 2

   Inspect Wiring and Connectors: Check the wiring harness leading to the DOC intake temperature sensor for chafing, melting, or loose connections that could cause a short circuit.

3. 3

   Check for Related Fuel/Emissions Codes: Look for active codes related to fuel injector leaks, rail pressure relief valves (e.g., 3915), or DPF/DOC restrictions, as unburnt fuel dumping into the exhaust will cause a genuine heat spike.

4. 4

   Inspect the Exhaust System: Check for physical signs of excessive heat (severe metal discoloration) or physical damage/melting to the DOC substrate.

1. 1

   Isolate Power

   Turn off the machine and disconnect the batteries to isolate the system and prevent electrical damage to the ECU.

2. 2

   Locate the Sensor

   Locate the DOC intake temperature sensor. It is positioned directly in the exhaust pipe, as close as possible to the DOC inlet.

3. 3

   Disconnect Wiring

   Carefully disconnect the electrical junction connector for the sensor.

4. 4

   Remove the Sensor

   Unscrew and remove the faulty temperature sensor from the exhaust pipe.

5. 5

   Install the New Sensor

   Thread the new DOC intake temperature sensor into the exhaust pipe and tighten the nut to the prescribed OEM torque specification.

6. 6

   Reconnect Wiring

   Reconnect the electrical connector. Ensure the harness cable is routed safely away from extreme heat sources and secured parallel to the reference plane (chassis/body structure).

7. 7

   Test and Clear

   Reconnect the batteries. Use a diagnostic tool to clear fault code 3887, start the engine, and verify that the temperature reads correctly and the code does not return.