New Holland 3656 – Engine ECU: Torque Limitation Caused by Particulate Filter

The Engine Control Unit (ECU) has limited the engine's torque output (limp mode) as a protective measure due to a detected issue with the Diesel Particulate Filter (DPF). This condition is triggered when the ECU detects that the DPF is overloaded with soot beyond a safe threshold and cannot be effectively cleaned through the normal automatic regeneration process. The power reduction is designed to prevent damage to the engine and after-treatment components.

• T4
• T5
• T7
• T8
• T4.120
• B95CTC
• B110C
• L220
• L225
• C232
• C238

1. 1

   Initiate a manual or 'forced' regeneration of the DPF via the cab switch or display menu (engine must be at operating temperature)

2. 2

   Inspect DPF differential pressure hoses for cracks, melting, soot blockages, or inner liner delamination

3. 3

   Check for exhaust leaks upstream of or at the DPF, which can alter pressure and temperature readings

4. 4

   Test the DPF differential pressure sensor for a 5-volt reference, ground, and signal. Back-probe the signal wire while revving the engine and compare against a physical pressure gauge

5. 5

   Review machine operation history for frequent short cycles or prolonged low-idling that prevent passive regeneration

1. 1

   Address underlying issues

   Repair any discovered issues like damaged pressure hoses, exhaust leaks, or a faulty sensor before proceeding with DPF servicing.

2. 2

   Perform a forced regeneration

   Using the operator's manual instructions or a diagnostic tool, attempt a forced regeneration after initial faults are addressed.

3. 3

   Replace DPF pressure sensor

   If the sensor is faulty, disconnect the electrical connector and hoses, remove the retaining clip/screw, install the new sensor, and clear related fault codes with a diagnostic tool.

4. 4

   Clean or replace DPF assembly

   If regeneration fails and the DPF remains clogged, remove the DPF assembly for professional cleaning or replace it with a remanufactured unit.