John Deere 3251.02 – ECU (Engine Control Unit): DPF Differential Pressure Signal Invalid

The controller has detected a relationship problem between the exhaust flow and the Diesel Particulate Filter (DPF) differential pressure. This code triggers when the DPF differential pressure sensor fails to respond correctly, or when the system identifies a discrepancy between the calculated exhaust flow and the actual differential pressure across the DPF. This typically indicates a sensor failure, blockage, or inaccuracies in data processing.

• 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
• 6105M
• 7200R
• 8R/RW Series (8245R to 8400R)
• 9RT Track Tractors (9470RT, 9520RT, 9570RT)
• Loaders and excavators utilizing John Deere PowerTech engines with DPF systems

1. 1

   Inspect the DPF System: Check the DPF and exhaust piping for signs of severe clogging, soot buildup, or physical damage that might restrict exhaust flow and skew differential pressure readings.

2. 2

   Inspect Electrical Connections: Check the DPF differential pressure sensor wiring harness and connectors for corrosion, loose pins, or potential shorts to power/ground that could cause an invalid signal.

3. 3

   Test the Differential Pressure Sensor: Use a diagnostic tool (like John Deere Service ADVISOR) to measure the actual signal output of the sensor and compare it to expected values under current operating conditions. Check for proper calibration against known pressure differentials.

4. 4

   Check Sensor Tubes: Ensure the metal tubes/hoses running from the exhaust to the differential pressure sensor are not plugged with soot or cracked.

1. 1

   Clear Blockages

   If the sensor tubes are plugged with soot, clean the passages thoroughly.

2. 2

   Replace Faulty Sensor

   If the sensor is found to be defective, unresponsive, or outputting erratic data, remove the old sensor and install a new DPF differential pressure sensor.

3. 3

   Reset the ECU

   After sensor replacement, use a diagnostic tool to reset the ECU and clear the 003251.02 fault code.

4. 4

   Perform System Tests

   Conduct a forced/service regeneration to confirm the system is accurately measuring DPF differential pressure and that the exhaust flow correlation is back within normal parameters.

5. 5

   Monitor Performance

   Monitor the DPF performance post-repair to ensure the code does not return and that passive regenerations are occurring normally.