Diesel Trouble Codes

P2457 — Exhaust Gas Recirculation (EGR) Flow Too Low (6.4 Power Stroke)

Diagnostic reference for 6.4L Power Stroke (2008-2010) P2457.

Updated September 2, 2026

What it means

On the 6.4L Power Stroke the generic definition is EGR flow lower than expected, but Ford defines P2457 for this engine family as EGR cooler bypass valve performance, not generic EGR flow low. The 6.4 has an EGR valve plus an EGR cooler; the cooler is a known failure point.1

Most likely causes

  1. EGR cooler bypass valve performance / control circuit fault — Ford defines P2457 on this platform as EGR cooler bypass valve performance. A low electrical signal to the cooler bypass valve is described for related codes P244B/P244A, indicating the PCM monitors the bypass valve control circuit.123
  2. EGR system flow/position faults affecting cooler bypass operation — The 6.4 EGR system includes valve and cooler; flow/position codes such as P0401 insufficient, P0402 excessive, P0404 range/performance are typical for this hardware.1456
  3. Aftertreatment/DPF related conditions influencing EGR operation — The 6.4 uses DOC plus DPF with active regeneration via late post-injection; DPF regeneration frequency code P2459 is valid for this platform.7

How to diagnose

  1. Verify code definition for this platform: confirm P2457 is EGR cooler bypass valve performance per Ford for 6.4L Power Stroke.
  2. Inspect EGR cooler bypass valve control circuit for electrical faults; related bypass valve circuit low codes are documented for this platform.
  3. Check EGR valve and cooler for flow/position issues consistent with 6.4 EGR hardware.
  4. Review aftertreatment status; DPF regeneration frequency and restriction can affect EGR operation on this DOC+DPF system.

Parts and tools you may need

Rough cost and difficulty

Parts and labor vary by region and shop; obtain local estimates.

When to see a pro

High-pressure fuel and emissions systems require professional service. If drivability is affected, have a qualified diesel technician diagnose and repair. Do not attempt repairs to safety-critical or high-pressure systems without proper training and tools.

Sources

  1. Curated DTC seed — 6.4 Power Stroke (curated) ↩︎ ↩︎ ↩︎

  2. Curated DTC seed — 6.4 Power Stroke (curated) ↩︎

  3. Curated DTC seed — 6.4 Power Stroke (curated) ↩︎

  4. Curated DTC seed — 6.4 Power Stroke (curated) ↩︎

  5. Curated DTC seed — 6.4 Power Stroke (curated) ↩︎

  6. Curated DTC seed — 6.4 Power Stroke (curated) ↩︎

  7. Curated DTC seed — 6.4 Power Stroke (curated) ↩︎