04 Nissan Xterra: PO400 Code


Old 05-03-11, 07:26 PM
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Join Date: Mar 2009
Location: USA
Posts: 176
04 Nissan Xterra: PO400 Code

I have a code that shows up as PO400. It is EGR Function- No/Low Flow. I have looked around online and mostly everyone has not had a problem with the EGR failing instead most blame blocked passages.

I honestly do not know what to do or where to start. What I wanted to do is take off the lines leading and coming out of the EGR, and one by one clean them out. Just I do not know what to use to clean them. The guy from the auto parts store said to use carburator cleaner to clean out the lines. I purchased it, just have not used it, yet.

If you think I should start some where else please feel free to guide me along the way. Or maybe other things that I should do to single out the problem.

The truck itself does not start at the first crank, It usually is the second time till it starts. Starts off rough (shaking) for about the first 13 seconds then goes away. The truck from there on is fine except for the shaking (as if it wants to turn off) at the stop light (About 3 times a day).In the freeway it is completely fine no problem at all. If I turn the car off and wait 1 minute it will hesitate till the second crank then it will start (With a strong smell of gas).If I turn it on immediately after I turn it off then I have no problem starting.

Any tips or suggestions are greatly appreciated.

Hope I did not leave out any information that could be of more help.

Before I forget the truck has 100,000 miles and I use 89 octane gas.
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Old 05-06-11, 02:10 PM
Join Date: Jul 2006
Location: Near Philly
Posts: 553
1. When were the plugs changed last?
2. If your engine doesn't require 89 octane, then you are wasting money.
Old 05-06-11, 02:47 PM
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What Bob said, plus, don't waste your time on the hoses going to the EGR. Replace the EGR. It has a flow function, too, and most likely the hoses and suction are fine.
Old 05-09-11, 07:34 PM
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Join Date: Mar 2009
Location: USA
Posts: 176
Looks like the problem was the Fuel Pressure Regulator.

I ended up giving in and had to take it to a friend that is a mechanic.

Now we will see if it fixed the problem. The part in coming in till tomorrow afternoon.
Old 05-11-11, 08:26 AM
Join Date: May 2011
Location: USA
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Definitely sounds like you need your egr system cleaned. Carb cleaner will do the trick. Just need to really get inside those hoses and pipes, and really flush the build up out. I've completely taken my egr valve out along with connecting hoses and pipes(ford f150 and 2000 range rover) and used carb or throttle body cleanera wire brush and pipe cleaner to get the job done.

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