Merlo 3 – ECU: DPF Clogged

The Diesel Particulate Filter (DPF) has accumulated a sufficient amount of soot to require a regeneration cycle. The Engine Control Unit (ECU) triggers this fault when the pressure differential between the DPF inlet and outlet exceeds a predefined threshold, indicating restricted exhaust flow. Failure to address this condition will lead to reduced engine performance, black smoke emissions, and may eventually force the machine into a limp mode to prevent engine damage.

• Kompakt
• Turbofarmer
• TF 30.9
• Schwerlast
• Multifarmer
• Panoramic
• P40.17
• Roto

1. 1

   Read fault codes using a diagnostic tool (e.g., MerloDiag) to confirm code 3 (J1939: 001236) and check for related DPF, temperature, or AdBlue sensor codes

2. 2

   Visually inspect the exhaust system for damage, leaks, or loose connections around the DPF, sensors, and hoses

3. 3

   Inspect the pressure hoses running to the DPF differential pressure sensor for cracks, kinks, soot blockages, or loose fittings

4. 4

   Examine the DPF differential pressure sensor's electrical connector and wiring for corrosion, damage, or loose pins

5. 5

   Perform a voltage test with the engine off (ignition on): back-probe the sensor's signal wire to verify a baseline voltage of approximately 0.5V

6. 6

   Perform a dynamic voltage test with the engine running: monitor the sensor's voltage, which should increase with engine RPM. If the voltage is stuck or reads zero, the sensor is likely faulty

1. 1

   Position the machine

   Park the machine on level ground in a safe, open area away from flammable materials. Lower any attachments to the ground.

2. 2

   Engage safety measures

   Apply the parking brake, place the transmission in neutral, and set the operating mode switch to the middle (or locked) position.

3. 3

   Meet system preconditions

   Ensure the engine coolant temperature is above 60-65°C (regeneration will not start if too cold) and turn off any high-load accessories like air conditioning.

4. 4

   Initiate manual regeneration

   Press and hold the DPF regeneration button on the dashboard for approximately 2 seconds. The engine RPM will automatically increase and hold at an elevated speed (e.g., 1700-1800 RPM).

5. 5

   Monitor the process

   Allow the regeneration process to run for 30 to 60 minutes without interruption. The process is complete when the engine speed returns to normal idle and the DPF warning light extinguishes.

6. 6

   Perform forced regeneration or replace DPF

   If manual regeneration fails to start, fails to complete, or the fault returns immediately, use a diagnostic tool (MerloDiag or Jaltest) to force a regeneration. If the DPF is heavily saturated with soot or ash, it must be professionally cleaned or replaced.