Diesel Trouble Codes

P2002 — Diesel Particulate Filter Efficiency Below Threshold (Bank 1) (6.4 Power Stroke)

Diagnostic reference for 6.4L Power Stroke (2008–2010) DPF efficiency below threshold.

Updated September 2, 2026

What it means

The PCM judges DPF filtering efficiency, using pressure/temperature data, to be below threshold. Generic definition: DPF filtering efficiency judged by pressure/temperature data is below threshold.1

Most likely causes

  1. DPF substrate degradation / ash overload reducing filtration efficiency — Aged or ash-loaded DPF can no longer meet efficiency targets even with normal delta-P. Platform has DOC+DPF aftertreatment with active regeneration via late post-injection; no SCR/DEF.1
  2. Excessive soot loading / chronic incomplete regeneration leading to efficiency loss — Repeated failed or short regens raise soot mass; platform DPF codes include P2463 soot accumulation and P2459 regen too frequent.23
  3. DPF differential pressure sensor or tubing fault causing incorrect efficiency calculation — Erroneous delta-P input makes PCM think efficiency is low. Platform DPF codes include P244A delta-P too low and P244B delta-P too high.1
  4. Exhaust leaks upstream of DPF (turbo/downpipe/DOC connections) diluting pressure/temperature signals — Leaks alter measured delta-P/temperature, skewing efficiency calculation. Platform has twin fixed-geometry sequential turbos, DOC+DPF, no VGT.4
  5. EGT sensor drift/fault affecting regen control and efficiency assessment — EGT sensors around DOC/DPF are used for regen control; faults are P0544/P0546 (EGT 1), P2032/P2033 (EGT 2).1
  6. DOC efficiency loss affecting downstream DPF performance — Platform maps P0420 to DOC (oxidation-catalyst) efficiency, not three-way catalyst. DOC degradation can influence DPF operation.5

How to diagnose

  1. Verify freeze-frame and monitor DPF differential pressure at idle and under load; compare to expected values. Platform DPF codes include P244A/P244B for delta-P faults.
  2. Inspect DPF differential pressure sensor and tubes for cracks, soot plugging, or moisture; check sensor output vs. manual gauge.
  3. Review recent regen history and frequency; frequent regens suggest incomplete burn. Platform code P2459 is regen frequency.
  4. Check EGT sensor readings for plausibility and response; platform uses several EGT sensors for regen control.
  5. Inspect exhaust system for leaks upstream of DPF (turbo outlet, downpipe, DOC connections). Platform has twin fixed-geometry sequential turbos.
  6. Assess engine oil for fuel dilution from excessive post-injection during regen; 6.4 is known for oil fuel dilution from late post-injection.

Parts and tools you may need

Rough cost and difficulty

Parts and labor vary by region and shop; DPF replacement or cleaning is typically high cost. NHTSA complaints show high repair costs for 6.4 fuel system and aftertreatment issues.

When to see a pro

If forced limited power or restriction codes appear (e.g., P246C), or if regeneration cannot be completed safely, have a qualified diesel technician evaluate the aftertreatment system. High-pressure fuel system work is safety-critical.

Sources

  1. Curated DTC seed — 6.4 Power Stroke (curated) ↩︎ ↩︎ ↩︎ ↩︎

  2. Curated DTC seed — 6.4 Power Stroke (curated) ↩︎

  3. Curated DTC seed — 6.4 Power Stroke (curated) ↩︎

  4. Curated DTC seed — 6.4 Power Stroke (curated) ↩︎

  5. Curated DTC seed — 6.4 Power Stroke (curated) ↩︎

Watch a repair

Third-party videos, not ours — for illustration. Confirm anything against the factory service information for your truck.

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