Diesel Trouble Codes

P0402 — Exhaust Gas Recirculation Flow Excessive (6.7 Power Stroke)

Diagnostic reference for P0402 on the 6.7 Powerstroke.

Updated September 1, 2026

What it means

Measured EGR flow is higher than commanded. Typical on this platform: stuck-open EGR valve or a sensor rationality fault.1

Most likely causes

  1. Stuck-open EGR valve — Valve fails mechanically open, allowing excess exhaust flow. Typical on this platform for P0402.1
  2. EGR position sensor / valve assembly rationality fault — Position feedback implausible versus command, causing the PCM to see excessive flow. Typical on this platform: EGR valve position sensor or the valve assembly.2
  3. EGR cooler obstruction / exhaust leak affecting flow measurement — Obstructed EGR cooler can alter flow characteristics; NHTSA report notes exhaust fumes inside vehicle with obstructed EGR cooler cord on a 2011 F-250 SD.3

How to diagnose

  1. Verify code and freeze-frame data; confirm P0402 is current and note engine conditions at set.
  2. Inspect EGR valve operation and position feedback using scan tool data; compare commanded vs actual position.
  3. Check EGR-related wiring and connectors for damage or corrosion; inspect for exhaust leaks near EGR components.
  4. Review related codes; e.g., EGR position sensor range/performance P046C may accompany P0402.

Parts and tools you may need

Rough cost and difficulty

Costs vary by region and labor; obtain local estimate.

When to see a pro

If diagnosis is inconclusive, or repair involves high-pressure fuel or brake systems, have a qualified diesel technician perform diagnosis and repair.

Sources

  1. Curated DTC seed — 6.7 Powerstroke (curated) ↩︎ ↩︎

  2. Curated DTC seed — 6.7 Powerstroke (curated) ↩︎

  3. NHTSA owner report 10510437 ↩︎

Watch a repair

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

Ford EGR Flow Testing (P0401, P0402, P0405) — ScannerDanner