Diesel Trouble Codes

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.

Updated September 2, 2026

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

  1. 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
  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

  1. Verify code and freeze frame; confirm P0402 is active on 6.7 Cummins 2007.5–2012 EGR+DPF pre-SCR.
  2. Inspect EGR valve operation and position feedback; compare commanded vs actual. Control circuit range/performance is P0404; stuck open is P042E.
  3. Check EGR passages/cooler for carbon blockage and valve mechanical binding.
  4. Review exhaust backpressure and DPF regen frequency; frequent regens indicated by P2459 — Diesel Particulate Filter Regeneration Frequency.
  5. Assess intake/exhaust leaks and sensor inputs; platform uses MAP primary load, MAF for EGR/emissions per platform facts.

Parts and tools you may need

Rough cost and difficulty

Parts and labor vary by region and shop; diagnostic time is typically 1–2 hours before parts replacement.

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.

Sources

  1. Curated DTC seed — 6.7 Cummins (EGR + DPF, pre-SCR) (curated) ↩︎

  2. Curated DTC seed — 6.7 Cummins (EGR + DPF, pre-SCR) (curated) ↩︎

  3. Curated DTC seed — 6.7 Cummins (EGR + DPF, pre-SCR) (curated) ↩︎

Watch a repair

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

2016 Ford 6.7L (P0402) — BL Automotive · 47K views

2019 6.7 Powerstroke EGR Maintenance: The Problem With Carbon Build-Up — Dave's Auto Center · 170K views

Ford EGR Flow Testing (P0401, P0402, P0405) — ScannerDanner · 699K views