P0401 Code


Old 10-09-07, 06:57 AM
Thread Starter
Join Date: Feb 2003
Location: Houston, TX
Posts: 45
P0401 Code

Hi All,

I have a 1997 RAV4 with the check engine light on. The code is P0401 for "EGR restricted flow".

Of course Autozone's knee-jerk reaction was that "the EGR valve is bad" but it seems to me that the flow could be restricted anywhere along the way - vsv, vacuum modulator or even carbon deposits which need to be cleaned out somewhere.

Could someone please give me a quick idea of the best way to diagnose exactly where the problem is rather than possibly replacing parts which are working fine? How could I test the various components to determine which is faulty?

Any assistance would be greatly appreciated!
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Old 10-09-07, 07:26 AM
billys68ss's Avatar
Join Date: May 2003
Location: USA
Posts: 1,459
You need the diagnostic procedure to properly diagnose this concern. I would call your local toyota dealer and see if there is a common issue with these systems. I cant remember if it were Toyotas or Hondas, but I remember a few years ago I had one that had a recall or TSB that applied. The EGR valve was replaced and the EGR Tube was thoroughly cleaned to eliminate any carbon that may be built up restricting flow. Usually the culprit is in fact the EGR valve, but sometimes there are carbon deposits that cause this issue.
Hope this is helpful to ya,

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