P0325 and P0400

An EGR valve that has failed, refuses to open (or the EGR passageway in the manifold is clogged) will allow elevated NOX emissions and may also cause a detonation (spark knock) problem


Knocking out the PO400 an EGR problem will most likely take out the PO325 dealing with the knock sensor.

Detonation is being cause by the EGR and causing the knock sensor to sense it.

`99 Max GXE 275,780 Miles 3.0 6cyl

I have changed to premium gas and the check engine light has gone out. Is this possible?

Also when I start up there is a whine that seems like it is in the belts. I lasts for a while until I press hard on the accelerator pedal really hard. There is a fume and some smoke initially. After that, the noise is intermittent. Is this a carborn build up problem?

Thanks

I had the same two codes and have only had the car about 6 months, I decided to check the air filter and I found a extremely dirty filter and enough debris to fill a dustpan! I cleaned out the debris and put a new filter in and it solved the problem.

Great addition to this thread! Please feel free to help out whenever you are on the site :)

Cheers, Ken

I went to a Nissan dealer because my repair engine soon light was on & he diagnosed both a P0325 - Knock Sen/Circuit and a P0420 - TW Catalyst Sys-B1. He gave me an estimate to fix both issues including parts, tax and labor totaling $2,416.00. He also said that my car would not pass inspection because "laptops store this info". Because I had been looking at cars on the lot while the diagnostics were being performed I am not sure that I really need this work done to pass inspection. It may be that they were just trying to get me to buy a car. I certainly do not want to invest $2400 in my '99 Maxima. Is what the dealer's service mgr. said true? The engine light is now off and has not come on since this visit on 10/10/08 (3,000 miles ago) and the car is running fine. Thanks.

Hello
Thanks for the donation.

In most states with emission test laws, that is true. If you have the check engine light on at all it will fail. Especially the codes you are getting. They would have to be repaired before you can pass. You will need to contact your local officials to confirm this in your specific area though.



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The knock sensor is always bad in this car it seems but that does not trigger the check engine light. The check engine light was probably for the oxygen sensor. Which if the light is off for the inspection it's not a worry. If you are getting bag gas mileage then I would look at that oxygen sensor to be replaces other than that o would not replace the sensor as well...