# maxima 97 EGR problem



## hacebe_mi (Jan 30, 2006)

Hello everybody. I am a new user. I have a 97 Nissan Maxima with 137K miles,which recently had a service engine light on. I took it to the dealer for diagnosis and this is what they advised: the code from diagnosis came out to be P040 EGR system.
The guy told me that there is large amounts of carbon build up in manifold, which needs to be cleaned followed by fuel induction service. He quoted me a price of $600. He also said that more work may be needed. I did not take my car back to the dealer as i cannot afford that kind of money. The car drives a little bit rough but apart from that everything seems OK. I checked the mileage as well after this problem surfaced, and it seems to be OK. 
Can anyone please advise me what i should do. Should i take my car to a local reputed mechanic and get the EGR system/fuel induction cleaned up? Also how can i tell if i need to replace the EGR valve (EGR valve costs $154+tax from dealer). Thanks in advance for the help.


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## brianw (Feb 25, 2004)

Try cleaning the EGR system yourself, the feeder tube to the manifold often gets clogged with deposits, and replace the EGR check valve ($5, I think). Pull the rubber hose off and clean it out. Might want to check maxima.org forums to see if they have any guides on this.


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## DRUNKHORSE (Mar 6, 2005)

flow codes are generally an issue with clogged EGR system ports. These ports must be thoroughly cleaned to prevent particles from sticking in the valve and keeping it open. check this page for how to test if your EGR valve needs to be serviced/ replaced. Also check this page so that you can clean out/ or have a mechanic clean out the manifold.


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## DRUNKHORSE (Mar 6, 2005)

I for got to add, I think autozone has it for 125, and if you do a search wether through "google" or "ask.com" you can easily find other parts stored that can sell it for cheaper. You can try ebay aswell and see what you can find. 

*additional info.*

Comparison chart for EGR to MAP values.example








10------------time(seconds)------------20

I know, I know, my art skills suck. but atleast I tried

you should also check the (MAP) sensor.
The position of the EGR effects manifold pressure. When the Egr valve open and the EGR flow occurs, manifold pressure increases(vacuum decreases). When the EGR valve is closed and EGR flow is zero. the manifold pressure decreases(vacuum increases). In both conditions, the amount of MAP change is relative to EGR flow.

The PCM will occasionally test the EGR system function under specific driving conditions. Typical testing is high speed driving(steady MAP reading and throttle postion) or deceleration. In the example above the EGR is completely closed(steady closed). Then the EGR is commanded full open, note the change in the MAP sensor reading/manifold vacuum.
This example shows the response of a properly working EGR system. IF the EGR valve opens, but EGR passages are clogged or the other components malfunction, correct the EGR flow is inhibited and may be reflected as such, by little or no activity from the MAP sensor during EGR operation.

*question.*
were there any other codes besides P0400 that might contribute to the P0400?


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## hacebe_mi (Jan 30, 2006)

DRUNKHORSE said:


> I for got to add, I think autozone has it for 125, and if you do a search wether through "google" or "ask.com" you can easily find other parts stored that can sell it for cheaper. You can try ebay aswell and see what you can find.
> 
> *additional info.*
> 
> ...


thanks drunk. The P0400 was the only code that came up according to the dealer diagnosis.


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