So I failed for code p0400 egr flow malfunction. I've had this code for 7 years now off and on but now I have to get it fixed. So what should I just take it to nissan since I have no other options and out of ideas?? Or should I try just buying an egr valve from the dealer and put it on myself and hope it just fixes it?

 

I doubt that you need a new valve.

Every 4th gen gets it, do this:

http://forums.maxima.org/4th-generat...ing-p0400.html

 

I never had that code...premium and occasional hard driving does not clog the EGR tube.

 

That is the true... Never had this problem either. Premium and plenty of hard driving here!

 

Doubt it's the gas since I was putting premium in it for a long time and still got the code.

 

Seafoaming the car might help...(just something to think about)

 

I can't attest to the hard (high rpm?) driving, but premium fuel does not prevent this problem. after 150k of shell vpower mine was plugged solid. I highly doubt hard driving would have prevented this.

however, running rich (e.g. stop and go city traffic) surely makes it worse. and since most of my miles have been in chicago traffic jams, well that makes sense...

seafoaming will do nothing. must physically clean (or if you're lazy like me, replace) the EGR tube.