John Deere 3936.16 – Engine Control Unit (ECU): Calculated Unintended Combustibles in DPF Moderately High

The engine's control system calculates that the level of unintended combustibles (such as unburned diesel fuel, engine oil, or excessive soot) inside the Diesel Particulate Filter (DPF) is moderately higher than expected. Active exhaust filter cleaning (regeneration) is disabled for safety reasons, and continued operation will result in an engine derate or commanded engine shut-off to prevent a thermal event or permanent damage.

• 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
• 8235R
• 8245R
• 8260R
• 8285R
• 8310R
• 8310RT
• 8335R
• 8335RT
• 8360R
• 8360RT
• 8400R
• 7760 Cotton Pickers/Strippers

1. 1

   Check for accompanying codes related to fuel injector leakage (e.g., ECU 000651.06) or fuel dosing system pressure faults (e.g., ECU 004077.07).

2. 2

   Check DOC temperatures for codes indicating abnormal Diesel Oxidation Catalyst inlet/outlet temperatures (e.g., 004765.12, 004766.12), which can confirm raw fuel is burning in the exhaust.

3. 3

   Perform a DPF Filter Cleanliness Test using a diagnostic service tool to verify if the DOC efficiency has been reduced.

4. 4

   Check engine oil level on the dipstick to see if the engine is making oil due to fuel dilution from a leaking injector.

1. 1

   Cycle Power

   Turn the tractor off, cycle the power, and turn it back on to see if the code clears or remains active.

2. 2

   Address Upstream Leaks

   If diagnostic checks reveal a leaking fuel injector or a faulty exhaust fuel dosing system, repair or replace those components first. If you do not fix the source of the fuel/oil leak, the new DPF will immediately become contaminated again.

3. 3

   Attempt Parked Regeneration

   If the DPF is not severely damaged and the upstream leak has been fixed, use the John Deere Service Advisor tool to command a parked regeneration (forced regen) to burn off the accumulated soot/combustibles.

4. 4

   Inspect/Replace the DPF

   If the DPF is heavily contaminated with raw fuel or oil (which cannot be safely burned off) or if the system refuses to regenerate, the DPF must be physically removed. It will need to be sent out for professional cleaning or replaced with a new/remanufactured unit.

5. 5

   Perform a Replacement Reset

   If the DPF or DOC is cleaned or replaced, you must use the diagnostic software to perform a 'Replacement Reset.' This resets the ECU's soot and ash accumulators. Failing to perform this reset can result in severe damage to the aftertreatment system.