This engine has restricted EGR passages in the intake manifold/throttle body. In this video I will show you the steps involved in identifying this problem. Many EGR valves, DPFE sensors and EVR solenoids get replaced needlessly for this problem. The engine being tested is a 4.6L on an OBD1 system however the procedures shown are the same for both OBD I and OBD II vehicles. The only difference is in the trouble code number. I believe the OBD II version of this 332 code is a P0401.

Engine Performance Diagnostics chapter 24

symptoms 50

  • check engine light with EGR flow codes
  • pinging/detonation problems at part throttle

fix 50

  • remove throttle body and clean intake passages

test shown enh 50

  • how to test a Ford DPFE sensor
  • how to test a Ford EVR solenoid
  • how to force the EGR valve to open (flow test)
  • how to test the computer driver for the EVR solenoid
  • how to verify proper vacuum supply to the EVR and EGR

Tools used

  • scan tool
  • digital voltmeter
  • hand vacuum pump
  • test light

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(Chapter 24) EGR Flow and System Tests

Related videos:

Ford EGR Flow Testing (P0401, P0402, P0405):


Ford EGR flow quick test (P0401) DPFE fault:


How to test an EGR DPFE sensor (EGR flow test) - Ford, Lincoln, Mercury :


Ford Ranger EGR Flow Trouble Code P0401 (DPFE fault):


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For more information on this topic, I have written a “field manual” called Engine Performance Diagnostics which is available as an eBook or paper book.

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