Diagnostic code P0400

1997 NISSAN TRUCK
178,000 MILES • 4 CYL • 2WD • MANUAL
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DWRIGHT956
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  • 1 POST
"Exhaust gas recirculation flow malfunction". What causes it and how can you fix it.
Dec 2, 2009 at 1:18 AM
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.
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BLUELIGHTNIN6
  • AUTOMOTIVE REPAIR CONTRIBUTOR
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Hello,

This happens when the EGR valve fails or the passages get clogged up and need to be cleaned out here is a video that shows how to check the valve and the location of the valve below.


https://youtu.be/DqUCbbKdWf4

Check out the diagrams (Below). Please let us know what happens.
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Dec 2, 2009 at 1:23 AM
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ENESHAD
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I had this problem got a new EGR for $98.00 all fixed I love this site.
Jul 18, 2019 at 12:38 PM
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MSANN
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po400/po446 problems what does this means and can i make the reparts myself...or how costly will it be..
Jul 18, 2019 at 12:38 PM (Merged)
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KHLOW2008
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Hi MSANN,

P0400 = Exhaust Gas Recirculation flow. Most probably the EGR passage is clogged. You need to clear it of carbon deposits.

P0446 = Evaporative Emission Control System vent control.

Not easy to handle yourself and the cost depends on any replacement parts needed.
Jul 18, 2019 at 12:38 PM (Merged)