P0402 — Exhaust Gas Recirculation Flow Excessive — 6.7 Cummins (EGR + DPF, pre-SCR)
Diagnostic reference for 6.7L Cummins 2007.5–2012 EGR+DPF pre-SCR.
What it means
The ECM has detected measured EGR flow higher than commanded. Generic definition: measured EGR flow is higher than commanded. Typical on this platform: 6.7L Cummins 2007.5–2012 EGR+DPF pre-SCR.1
Most likely causes
- EGR valve stuck open / mechanically binding — Valve fails to close, causing continuous high EGR flow. Related platform code for stuck open is P042E — Exhaust Gas Recirculation Control Stuck Open.2
- EGR valve position sensor / feedback error — Incorrect position feedback makes ECM think flow is excessive. Control circuit range/performance issues are covered by P0404 — EGR control circuit operating outside expected range or performance.3
How to diagnose
- Verify code and freeze frame; confirm P0402 is active on 6.7 Cummins 2007.5–2012 EGR+DPF pre-SCR.
- Inspect EGR valve operation and position feedback; compare commanded vs actual. Control circuit range/performance is P0404; stuck open is P042E.
- Check EGR passages/cooler for carbon blockage and valve mechanical binding.
- Review exhaust backpressure and DPF regen frequency; frequent regens indicated by P2459 — Diesel Particulate Filter Regeneration Frequency.
- Assess intake/exhaust leaks and sensor inputs; platform uses MAP primary load, MAF for EGR/emissions.
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
- Scan tool with live EGR commanded vs actual data
- EGR valve position sensor data
- Exhaust backpressure gauge
- Inspection light and borescope
Tools you’ll need
- bi-directional scan tool — Command EGR valve position and compare commanded vs actual feedback to confirm excessive flow on 6.7 Cummins.
- digital multimeter — Verify EGR valve position sensor voltage and control circuit integrity against spec.
- exhaust backpressure gauge — Measure DPF restriction that can drive EGR flow higher than commanded.
- borescope — Inspect EGR valve seat and passages for carbon buildup causing stuck-open or flow imbalance.
Rough cost and difficulty
| Likely repair | Parts | Shop labor | Who usually does it |
|---|---|---|---|
| EGR valve/passage carbon cleaning | $20–$100 | 1–4 hrs | DIY with tools and a manual |
| MAP/boost pressure sensor | $40–$200 | 0.3–1 hrs | Easy DIY |
| EGR position/temperature/differential pressure sensor | $60–$300 | 0.5–1.5 hrs | DIY with tools and a manual |
| DPF differential pressure sensor | $80–$300 | 0.5–1.5 hrs | Easy DIY |
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 EGR valve removal or high-pressure fuel system work is required, have a qualified diesel technician perform it. Do not service high-pressure fuel lines or safety-critical systems without proper training and tools.
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
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