P2002 - Diesel Particulate Filter Efficiency Below Threshold (Bank 1)
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System
Powertrain (Engine & Gearbox)
OBS!This code is in a manufacturer-specific range. The description may vary depending on the vehicle manufacturer.
Related Fault Codes
Technical Description
P2002 is stored when the Engine Control Module (ECM) detects that the Diesel Particulate Filter (DPF) efficiency is below the calibrated threshold. The ECM monitors DPF performance primarily through the DPF Differential Pressure Sensor. If the pressure drop across the filter is lower than expected (suggesting a damaged, removed, or bypass-leaking filter) or if the soot accumulation rate deviates from the modeled values, the code is triggered. This fault directly affects NOx and PM emissions and may prevent active regeneration.
Possible Causes
Leaks or damage to the differential pressure sensor hoses (cracks/melted lines)
Faulty DPF differential pressure sensor (incorrect internal calibration)
Clogged or physically damaged/melted Diesel Particulate Filter (DPF)
Exhaust leak upstream of or near the DPF
Faulty ECU software or defective exhaust gas temperature sensors
Symptoms
Recommended Solution
- STEP 1: Visually inspect the hoses connecting the DPF to the differential pressure sensor for cracks, melting, or blockages. Check the exhaust system for leaks.
- STEP 2: Use a diagnostic tool to monitor live data for DPF differential pressure. At idle, it should be approx. 0.5-1.5 psi (3-10 mbar). If the reading is 0 or static during acceleration, the sensor or hoses are faulty. Verify 5V reference voltage and ground.
- STEP 3: Perform a forced DPF regeneration if soot levels are within safe limits. Ensure exhaust temperature sensors reach at least 600°C (1112°F) during the cycle.
- STEP 4: If hoses and sensors are functional but the code persists, the DPF may be physically compromised (cracked substrate) or require professional cleaning/replacement.
Mechanic's Tip
Before replacing expensive components, always double-check wiring and connections. 80% of all sensor faults are actually due to corroded contacts or broken wires.
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