John Deere 5018 – Engine Control Unit (ECU): Calculated Unintended Combustibles in DOC Extremely High

The system has calculated that an extremely high level of unburned fuel, oil, or other unintended combustibles has entered the Diesel Oxidation Catalyst (DOC). This condition causes unexpected and potentially dangerous temperature spikes in the exhaust filter, prompting the system to limit engine power (derate) and disable active exhaust filter cleaning (regeneration).

• 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
• 5095M
• 5105M
• 8245R through 8400R
• 9470RT
• 9520RT
• 9570RT
• 650K Dozers
• 7760 Cotton Pickers

1. 1

   Inspect the fuel system for leaking fuel injectors or incorrect injection timing that would allow raw, unburned fuel to pass into the exhaust stream

2. 2

   Verify combustion efficiency by checking for intake restrictions, EGR valve issues, or loss of compression that could cause incomplete combustion

3. 3

   Check for oil or coolant leaks by inspecting the turbocharger seals and head gasket

4. 4

   Inspect the DOC physically for signs of internal melting, face plugging, or excessive soot/ash buildup

5. 5

   Verify sensor integrity to ensure the exhaust temperature sensors and DOC/DPF pressure sensors are reading accurately and not falsely triggering the code

1. 1

   Resolve the Root Cause

   Repair the underlying issue causing the contamination (e.g., replace leaking fuel injectors, rebuild a leaking turbocharger, or fix EGR faults).

2. 2

   Service the DOC

   If the DOC is heavily contaminated with raw fuel/oil or physically damaged, it cannot be regenerated and must be removed. Clean the DOC (via professional DPF/DOC ultrasonic/bake cleaning services) or replace it entirely.

3. 3

   Clear the ECU

   Turn the ignition key off and on, and use a diagnostic tool to reset the ECU and clear the active 005018.00 fault code.

4. 4

   Perform a Parked Regeneration

   Once the root cause is fixed and the code is cleared, initiate a parked exhaust filter cleaning via the machine's CommandCenter/display.

5. 5

   Monitor System

   During the parked cleaning, monitor the exhaust temperatures and combustible levels to ensure they return to normal operating ranges.