New Holland ENG 3978 – Engine ECU: Particulate Matter Catalyst (PMCat): Signal range check flow resistance of the particulate filter - High

The soot load inside the Diesel Particulate Filter (DPF) / Particulate Matter Catalyst is too high. The engine control system has detected that the exhaust flow resistance across the filter has exceeded the expected normal range, triggering a 'Level 2 of PFlt Over-loaded' condition, which may result in an 'ATS Fail' message and a crank-but-no-start condition.

• C227
• C232
• L221
• L223
• L228
• SR210
• SR240
• SV280
• TR270
• TR310
• W50C ZB
• W60C ZB
• W70C HS
• W70C
• W80C HS
• W80C

1. 1

   Check operating history for excessive idling, lugging, or low-RPM operation that prevents passive regeneration

2. 2

   Verify regeneration history to see if the machine recently failed to complete automatic regenerations

3. 3

   Look for accompanying codes such as ENG 3979 (Flow resistance - Very High) or ENG 3981 (DOC-In temperature under 220°C during regeneration) which point to further aftertreatment failures

1. 1

   Connect Diagnostic Tool

   Connect a laptop with the CNH Electronic Service Tool (EST) software to the machine's diagnostic port.

2. 2

   Verify Soot Load

   Check the current soot load percentage and differential pressure sensor readings in the Engine ECU to confirm the DPF is overloaded but not permanently damaged.

3. 3

   Perform a Service Regeneration

   Use the EST software to command a complete 'Service Regen' (forced regeneration). The machine will elevate RPMs and inject fuel into the exhaust stream to burn off the accumulated soot.

4. 4

   Post-Regen Operation

   Once the service regen clears the code, instruct the operator to run the machine hard at Wide Open Throttle (WOT) under load to maintain high exhaust temperatures and prevent immediate soot buildup.

5. 5

   Replace if Failed

   If the service regeneration fails, the filter is face-plugged, or the internal catalyst is damaged, the DPF/PMCat assembly must be physically replaced.