John Deere 5018.16 – Engine Control Unit (ECU): Calculated Unintended Combustibles in DOC Moderately High

The engine controller has detected that the calculated level of unburned fuel or other unintended combustibles entering the Diesel Oxidation Catalyst (DOC) is moderately higher than expected. This condition indicates possible contamination in the DOC, which can severely affect the performance of the exhaust aftertreatment system, lead to unexpectedly high exhaust temperatures, and disable active exhaust filter cleaning. Continued operation with this active code will result in a loss of machine availability (derate or shutdown).

• 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
• 9470RT
• 9520RT
• 9570RT
• 7760
• D24x40 S3
• D40x55

1. 1

   Inspect the Fuel System: Check for issues in the fuel injection system that might cause unburned fuel to enter the exhaust stream (e.g., leaking fuel injectors or incorrect injection timing).

2. 2

   Verify Combustion Efficiency: Ensure the engine is not suffering from incomplete combustion (e.g., check intake air systems, turbocharger performance, and cylinder compression).

3. 3

   Inspect the DOC: Visually inspect the Diesel Oxidation Catalyst for signs of physical damage, face plugging, blockages, or excessive soot/fuel buildup.

4. 4

   Check the Exhaust System: Look for any exhaust leaks upstream of the DOC that could alter sensor readings or allow unintended combustibles to enter the system.

5. 5

   Review Operating Conditions: Evaluate driving patterns. Excessive idling or light-load operations can prevent the exhaust from reaching the temperatures required to naturally burn off combustibles.

1. 1

   Address the Root Cause

   Repair or replace any faulty engine components identified during diagnostics (e.g., replace leaking fuel injectors, fix intake leaks). Do not replace the DOC without fixing the upstream fuel issue, or the new DOC will also become contaminated.

2. 2

   Service the DOC

   Depending on the severity of the contamination, the DOC must either be professionally cleaned (baked/blown out) or completely replaced.

3. 3

   Reassemble the Exhaust

   If the DOC was removed, reinstall it using new OEM V-clamps and exhaust gaskets to prevent leaks.

4. 4

   Reset the ECU

   Use a John Deere Service ADVISOR tool (or equivalent diagnostic scanner) to clear the fault code and reset the ECU's aftertreatment learned values.

5. 5

   Monitor the System

   Perform a forced stationary regeneration (if permitted by the ECU) or operate the machine under load. Monitor the system to ensure exhaust temperatures and combustible levels return to normal ranges.