P2002 — Diesel Particulate Filter Efficiency Below Threshold (Bank 1) — 6.7 Cummins (EGR + DPF, pre-SCR)
Diagnostic reference for 6.7 Cummins 2007.5–2012 EGR+DPF pre-SCR. P2002 indicates the ECM judges DPF filtering efficiency below threshold using…
What it means
The ECM has determined DPF filtering efficiency is below threshold based on pressure/temperature data. Generic definition: DPF filtering efficiency, judged by pressure/temperature data, is below threshold. Platform has EGR + DOC/NAC + DPF, no SCR/DEF.1
Most likely causes
- DPF physically restricted / ash loaded, causing abnormal differential pressure and reduced efficiency — Excess soot/ash raises delta-P and temperature profile; ECM interprets as efficiency below threshold. Generic definition ties efficiency to pressure/temperature data.1
- DPF differential-pressure sensor or its tubing giving skewed readings — Erroneous delta-P input can cause false efficiency calculation. DPF pressure sensor circuit faults are documented for this platform.2
- Insufficient or failed regenerations leading to accumulated soot — Frequent or missed regens are a known DPF health driver on this platform. Regeneration frequency monitoring exists.3
- Excessive oil consumption / injector over-fueling increasing soot load — More soot production raises DPF load and efficiency monitor. Injector circuit faults are tracked on this platform.4
- Aftertreatment temperature sensing error affecting efficiency calculation — Efficiency monitor uses temperature data; sensor drift can bias the calculation. Generic definition references pressure/temperature data.1
- ECM / calibration / aftermarket tuning misreporting efficiency — Atypical catalyst/efficiency codes can appear with non-standard calibrations. P0420 is noted as atypical/rare and often misapplied on this platform.5
How to diagnose
- Verify freeze-frame and confirm P2002 is active with DPF-related data present.
- Inspect DPF differential-pressure sensor and tubes for soot plugging, cracks, or leaks; compare sensor voltage to spec at idle and elevated RPM.
- Review regen history and frequency; excessive regen frequency points to loading issues.
- Check exhaust backpressure and temperature sensor readings for plausibility vs. expected values.
- Inspect for oil consumption, blow-by, injector balance, and fuel system health; injector faults are monitored on this platform.
- Confirm calibration/ECM software is OEM for 2007.5–2012 EGR+DPF pre-SCR; non-OEM tuning can cause spurious efficiency codes.
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
- DPF differential-pressure sensor and tubing
- Exhaust backpressure test gauge
- Scan tool with Cummins enhanced data: DPF delta-P, temps pre/post DPF, regen status/counters
- Basic hand tools for sensor inspection
Tools you’ll need
- OBD-II scan tool — Read P2002 freeze-frame and monitor live DPF differential pressure, exhaust temps, and regen status to confirm efficiency fault conditions.
- Digital multimeter — Verify DPF differential-pressure sensor supply, ground, and signal voltages against spec at idle and elevated RPM to detect skewed readings.
- Exhaust backpressure gauge — Measure actual exhaust backpressure pre/post DPF to confirm physical restriction or ash loading versus sensor-reported values.
- Borescope — Visually inspect DPF substrate and inlet for plugging, melting, or ash accumulation without removal.
Rough cost and difficulty
| Likely repair | Parts | Shop labor | Who usually does it |
|---|---|---|---|
| Scan-tool forced (parked) regeneration | — | 0.5–1.5 hrs | DIY with tools and a manual |
| DPF differential pressure sensor | $80–$300 | 0.5–1.5 hrs | Easy DIY |
| DPF professional cleaning (bake and blow) | $300–$700 | 1–3 hrs | Shop |
| DPF / NOx-adsorber assembly replacement | $2,500–$6,000 | 1–4 hrs | Shop |
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 diagnosis points to internal DPF failure, removal and professional cleaning/testing is required. Do not attempt high-pressure fuel system service; CP3 high-pressure pump failures have caused sudden engine stoppage under load. See a professional for aftertreatment service and fuel system work.
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
Curated DTC seed — 6.7 Cummins (EGR + DPF, pre-SCR) (curated) ↩︎ ↩︎ ↩︎
Curated DTC seed — 6.7 Cummins (EGR + DPF, pre-SCR) (curated) ↩︎
Curated DTC seed — 6.7 Cummins (EGR + DPF, pre-SCR) (curated) ↩︎
Curated DTC seed — 6.7 Cummins (EGR + DPF, pre-SCR) (curated) ↩︎
Curated DTC seed — 6.7 Cummins (EGR + DPF, pre-SCR) (curated) ↩︎
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