John Deere 4765 – ECU: Diesel Oxidation Catalyst (DOC) Inlet Temperature is Extremely High

The system has detected that the temperature at the DOC inlet is higher than expected. Excessively high temperatures at the DOC inlet can be indicative of underlying issues such as excessive fuel injection, improper combustion, or exhaust system malfunctions. If operation continues without reducing the load, it can lead to machine failure.

• 5085E
• 5090E
• 5090EL
• 5100E
• 5085M
• 5100M
• 5100MH
• 5100ML
• 5115ML
• 5090M
• 5115M
• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R

1. 1

   Perform a Cold Soak Sensor Compare Check: Let the machine sit for at least four hours. Turn the key switch to ON (engine OFF) and compare DOC Inlet, DPF Inlet, and DPF Outlet temperatures. All should read within 10°C (50°F) of each other. A significant variance indicates a faulty sensor or circuit.

2. 2

   Inspect wiring and connections associated with the DOC inlet temperature sensor for damage, fraying, or looseness.

3. 3

   Check the sensor and its surroundings for contaminants that could skew temperature readings.

4. 4

   Test the sensor circuit using a multimeter or diagnostic tool for continuity and correct voltage levels.

1. 1

   Reduce Load

   Immediately reduce the engine load to prevent damage to the exhaust filter system.

2. 2

   Cool Down

   CAUTION: The exhaust filter may be extremely hot. Allow the exhaust filter to cool completely before attempting removal to prevent serious burns.

3. 3

   Disconnect Power

   Disconnect the battery negative (—) cable.

4. 4

   Remove Harness

   Locate the DOC Inlet Temperature Sensor on the exhaust filter assembly. Disconnect the wire connectors and leads.

5. 5

   Replace Sensor

   Remove the faulty DOC inlet temperature sensor and install the replacement part.

6. 6

   Reassemble

   Reconnect the wire harness. Install hold-down clamps and tie straps at their previous locations to secure the wiring.

7. 7

   Restore Power & Clear Codes

   Reconnect the battery negative cable. Reset the ECU to clear the fault code and run the engine to monitor the system, ensuring accurate temperature measurement.