P2002 — Diesel Particulate Filter Efficiency Below Threshold
P2002 sets when the DPF is not removing particulate matter at the expected efficiency, based on differential pressure or other monitoring methods. Leak and sensor proof before DPF condemnation. True efficiency failures are less common than sensor or leak issues.
Fault Overview
Damaged or melted DPF, cracked substrate, excessive ash, failed DP sensor, exhaust leaks around the DPF, and incomplete monitoring conditions are the primary causes. Always inspect for exhaust leaks at the DPF flanges. A melted DPF often has a history of extreme temperature events.
Engine & Platform Coverage
Symptoms
- •P2002
- •DPF efficiency low
- •particulate filter efficiency
- •P2002 DPF failed
Possible Causes
- 1.Damaged or melted DPF substrate
- 2.Cracked substrate
- 3.Excessive ash
- 4.Failed DP sensor
- 5.Exhaust leaks around the DPF
- 6.Incomplete monitoring conditions
Wiring & Circuit Notes
DP sensor circuits.
DVOM Specs & Sensor Tests
DP behavior. Post-cleaning or post-regen efficiency data. Visual/borescope inspection results.
Diagnostic Flow — FSM Sequence
AI Diesel Tech enforces this evidence-gate sequence. Each gate must pass before advancing.
4 steps locked behind Technician Mode- 1Step 1 — Verify DP Sensor Accuracy and Hoses: Verify DP sensor accuracy and inspect hoses and ports for blockage or leaks.
- 2Step 2 — Check for Exhaust Leaks at DPF: Check for exhaust leaks at DPF flanges and connections. Leaks can cause false efficiency readings.
- 3Step 3 — Perform Regen or Cleaning and Re-Evaluate: Perform a forced regen or professional cleaning and re-evaluate efficiency.
- 4Step 4 — Borescope or Remove for Inspection if Efficiency Remains Low: If efficiency remains low after cleaning, borescope or remove the DPF for physical inspection.
- 5Step 5 — Replace DPF Only After Proof of Damage: Replace the DPF only after physical damage is confirmed.
Unlock the full evidence-gated diagnostic sequence, DVOM test steps, and repair procedures in Technician Mode.
Full Diagnostic Access
Verification steps, preventative measures, severity guidance, and legacy comparison are available in Technician Mode.
Typical Repair Costs
Repair leaks $100–400; service DP sensor $80–300; clean DPF $200–600; replace DPF $1,500–3,500+.
Start Diagnosing This Fault Now
AI Diesel Tech walks you through every evidence gate in the correct order. Choose the plan that fits your shop.
AI Diesel Tech — The Technician's Diagnostic Engine
AI Diesel Tech diagnostic logic is built by an ASE Certified Diesel Technician and engineered for professional shop use. Trusted by technicians nationwide — used in shops, fleets, and training programs.
Summary
Use the AI Diesel Tech diagnostic engine to run this code through a structured, evidence-gated sequence and get a confirmed root cause before any parts are replaced.