Diesel Trouble Codes

P0402 — Exhaust Gas Recirculation Flow Excessive — 6.7 Powerstroke

Diagnostic reference for P0402 on 6.7 Powerstroke (2011–present).

Updated October 15, 2026

What it means

Measured EGR flow is higher than commanded.1

Most likely causes

  1. Stuck-open EGR valve — Valve remains open, allowing excess exhaust into intake.12
  2. EGR position sensor rationality fault — Position feedback implausible versus command, causing over-flow detection.13
  3. Soot binding / carbon buildup affecting valve operation — Soot can hold the valve open or prevent proper closure.2
  4. EGR valve assembly fault — Valve assembly or internal position sensor malfunction.3
  5. EGR cooler restriction contributing to flow anomaly — Cooler issues can affect flow characteristics; sometimes noted with stuck-open conditions.2

How to diagnose

  1. Verify code and freeze-frame data; confirm P0402 is active and note engine conditions.
  2. Inspect EGR valve operation and position feedback using scan tool; compare commanded vs actual position.
  3. Check EGR position sensor circuit range/performance for rationality faults.
  4. Inspect for soot binding or carbon buildup affecting valve closure.
  5. Review related EGR codes (e.g., P042E stuck open, P046C position sensor) for pattern.
  6. Assess intake and boost sensor data for rationality, as MAP/BARO faults can affect EGR control calculations.

Common mistake to avoid

Replacing the EGR valve without testing it. If the valve still moves freely, a carbon cleaning often fixes the flow code; and if it opens on command but the code stays, the blockage is in the passages or cooler, not the valve. Source: FleetRabbit — EGR valve problems and repair.

Parts and tools you may need

Tools you’ll need

Rough cost and difficulty

Likely repairPartsShop laborWho usually does it
EGR valve/passage carbon cleaning$20–$1001–4 hrsDIY with tools and a manual
EGR position/temperature/differential pressure sensor$60–$3000.5–1.5 hrsDIY with tools and a manual
EGR valve$150–$7002–4 hrsDIY with tools and a manual
EGR cooler$400–$9003–6 hrsShop

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 is inconclusive or internal EGR components require removal, consult a qualified diesel technician.

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 — 6.7 Powerstroke (curated) ↩︎ ↩︎ ↩︎

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

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

Repair videos: P0402 on the 6.7 Power Stroke

Third-party videos, not ours — picked for this engine. 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