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 October 15, 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 compound turbos (VGT high-pressure, fixed low-pressure), DOC+DPF.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 compound turbos (VGT high-pressure, fixed low-pressure).
  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.

Common mistake to avoid

Cleaning or replacing the DPF before checking its pressure sensor and tubes. Cracked, melted, plugged or wet sensor tubes, or a failing sensor, can set DPF codes while the filter itself is fine. They are cheap to check; clear and verify them before touching the filter. Source: FleetRabbit — P2002 DPF efficiency code causes and fixes.

Parts and tools you may need

Tools you’ll need

Rough cost and difficulty

Likely repairPartsShop laborWho usually does it
Scan-tool forced (parked) regeneration—0.5–1.5 hrsDIY with tools and a manual
Exhaust gas temperature sensor$50–$2500.5–1.5 hrsDIY with tools and a manual
DPF differential pressure sensor$80–$3000.5–1.5 hrsEasy DIY
Exhaust manifold, gasket or up-pipe leak repair$50–$4002–6 hrsDIY with tools and a manual

Typical US independent-shop figures; labor runs about $120–$180 per hour (dealers charge more). Confirm the diagnosis before buying parts.

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.

Check for recalls

Recalls are tied to your truck’s VIN, so check yours directly: enter the VIN at NHTSA’s recall lookup. Open safety recalls are repaired free at a dealer.

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) ↩︎