P0401 – EGR Flow Insufficient

Description

The EGR system is not flowing enough exhaust gas.

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Symptoms

  • Rough idle
  • Hesitation
  • Poor acceleration
  • High NOx emissions
  • Check engine light

Causes

  • Clogged EGR passages
  • Faulty EGR valve
  • Vacuum leak
  • Faulty DPFE sensor
  • Carbon buildup

Diagnosis

  • Inspect EGR valve
  • Check vacuum lines
  • Test DPFE sensor
  • Inspect passages
  • Scan live data

Repair

  • Clean EGR passages
  • Replace EGR valve
  • Fix vacuum leaks
  • Replace DPFE sensor
  • Remove carbon buildup

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