P2002 on VAG TDI – DPF Efficiency Below Threshold

Platform notes for VW/Audi/SEAT/Skoda diesels where P2002 often points to regen history, sensor plausibility or a DPF that can’t recover.

How It Commonly Shows Up on VAG

  • DPF light or engine light after a period of short trips / town driving.
  • Cooling fans running after shutdown, slightly higher idle, or frequent regen attempts.
  • Often appears with EGR codes or differential pressure sensor faults.

High-Probability Causes

  • Repeated interrupted regenerations (driving profile issue).
  • Differential pressure sensor or blocked pressure pipes giving false high readings.
  • EGR issues increasing soot output (P0401-type patterns).
  • Boost leaks / underboost reducing exhaust temperature, making regen harder.
  • DPF physically at end-of-life (high ash load) – cleaning or replacement required.

Quick Test Plan

  1. Read soot load, ash load, regen counters and last-regeneration distance/time (tool dependent).
  2. Check differential pressure readings at idle and at ~2,500rpm for plausibility.
  3. Inspect pressure sensor pipes for blockage or cracking.
  4. Check for EGR-related faults and boost control faults that drive soot up.
  5. Only attempt forced regen once the root cause is addressed and sensor readings are believable.

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