John Deere 4765.12 – ECU: DOC Inlet Temperature Sensor Issue / DOC Inlet Temperature Fault

This code is triggered when the exhaust filter temperature module detects a problem with measuring the temperature at the inlet of the Diesel Oxidation Catalyst (DOC). It typically indicates a sensor circuit failure, a plausibility error, or an unresponsive sensor. When this code is active, the engine controller will disable active exhaust filter cleaning (regeneration). Continued operation without resolving the issue will result in limited engine performance (derate) and eventual loss of machine availability.

• 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
• 6110M to 6195M
• 6110R to 6215R
• 7210R
• 7230R
• 7250R
• 7270R
• 7290R
• 7310R
• 8310RT
• 8335RT
• 8360RT
• 7760 Cotton Pickers
• 210G/GLC Excavators
• 450K/550K Dozers

1. 1

   Visual Inspection: Inspect the wiring harness and connectors associated with the DOC inlet temperature sensor. Look for damaged, frayed, or loose wiring.

2. 2

   Check for Contaminants: Ensure that the sensor and its immediate surroundings are free from heavy soot buildup or contaminants that could insulate the sensor and affect temperature readings.

3. 3

   Circuit Testing: Use a multimeter or diagnostic tool to test the sensor circuit for continuity, shorts to ground, shorts to battery, and correct voltage levels.

4. 4

   Live Data Monitoring: Connect a diagnostic tool and monitor the DOC inlet temperature live data. Start the engine; if there is no temperature change after engine startup, the sensor is unresponsive and likely failed.

1. 1

   Power Down

   Turn the machine off and disconnect the battery if repairing wiring. Ensure the exhaust system has cooled down completely to avoid severe burns.

2. 2

   Wiring Repair

   If the diagnostic checks revealed frayed wires or a loose connector, repair the wiring harness or replace the connector pigtail as necessary.

3. 3

   Sensor Replacement

   If the circuit is intact but the sensor failed the live data test, locate the DOC Inlet Temperature Sensor on the aftertreatment device (usually the first temperature sensor port on the exhaust filter assembly). Remove the faulty sensor and install the new one.

4. 4

   Clear Codes

   Reconnect the battery (if disconnected) and turn the key to the ON position. Use a diagnostic tool to reset the ECU and clear the 004765.12 fault code.

5. 5

   Verify Repair

   Start the engine and monitor the system to ensure the DOC inlet temperature reads accurately as the exhaust heats up. Verify that the active exhaust filter cleaning system is no longer disabled.