99' Expedition code P0401 - code returned after cleaning

[jvmagic]

Hi,

My Epedition has 180k miles and runs great except for this code. I followed the instructions (link below) I found on youtube and cleaned it rather well (all the buildup was gone from the ports I could see).

P0401 code ford Throttle body EGR port cleaning 4.6 Ford Expedition

After putting it back together and passing smog, the code came back after 15 days. Did I miss something? Was I suppose to take more of this apart and clean more thorough?

Thanks in advance.

~JV

 

[docraymund]

You need to check the egr valve itself and the hose that connects to it.

 

[1955moose]

By checking egr valve itself, vaccum pump check it to be sure it holds vacuum and doesn't drop on guage. To check if port through intake is clear warm vehicle apply vaccum to egr, idle should stumble and want to die. Also check electronic solenoid on back of egr, to be sure it's functioning proper.


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[Bedrck47]

P0401 - EGR Flow Insufficient Detected

The EGR system is monitored during steady state driving conditions while the EGR is commanded on. The test fails when the signal from the DPF EGR sensor indicates that EGR flow is less than the desired minimum.


Possible Causes

• Vacuum supply
• EGR valve stuck closed
• EGR valve leaks vacuum
• EGR flow path restricted
• EGRVR circuit shorted to PWR
• VREF open to DPF EGR sensor
• DPF EGR sensor downstream hose off or plugged
• EGRVR circuit open to PCM
• VPWR open to EGRVR solenoid
• DPF EGR sensor hoses both off
• DPF EGR sensor hoses reversed
• Damaged EGR orifice tube
• Damaged EGRVR solenoid
• Damaged PCM

 

[Bedrck47]

http://easyautodiagnostics.com/ford/4.6L-5.4L/how-to-test-the-egr-system-1

http://www.expeditionforum.com/threads/about-egr-pcv-dpff-evap-iat-tps-maf.23583/