Trouble Codes P0171 & P0174
 

Hey all, I'm getting P0171 and P0174 codes thrown on my 2011 with 150k miles on it. I've searched the forum and am not finding any information here. I have googled a lot and have found a lot of information but nothing specific to a 7th gen Maxima.

P0171 is a lean Bank 1 condition and P0174 is a lean Bank 2 condition. Does anyone have any ideas other than O2 sensors. I've had tried two different MAF sensors, the original OEM and an aftermarket sensor. I bought the aftermarket sensor when I was having a P0101 code but it turned out I needed to have the firmware flashed.

I would like to rule out the MAF, but I'm not 100% certain I can at this point. Has anyone had experiece with these codes?

Thanks much!

Could it well be a vacuum leak somewhere making the A/F mixture lean. I would look carefully in the engine bay while someone revs the engine few times. O2 sensors going out would be the next step if vacuum leaks are negative. Are you sure off the clamps around the throttle body are tightly secured?
Please report back.

mahanddem, I'll take a look tonight when I get home and get back.

For anyone who might be getting the trouble codes I mentioned when I started this thread I was finally able to chase the issue down. There are two hoses behind the intake manifold and one of those had degraded and had a massive hole in it. See the attached picture.

I went to the local auto parts store and got some 3/8" vacuum rated hose and replaced it. Codes are gone and my Maxima is running better than ever.
https://cimg0.ibsrv.net/gimg/maxima....5c32072a5.jpeg
Hosebfail

THANK YOU for reporting back to tell people how you solved it. I hate it when people come on a site expecting free help, but then can't be bothered to come back and say what the problem was, to help other people out. I had the same codes, and spent hours checking all kinds of stuff that people online were suggesting. I had seen this thread, but I didn't see any worn hoses on my car so I dismissed the idea. But after a couple more hours of trying this-and-that, I noticed a hissing noise at the passenger side rear of the engine compartment. I moved my ears this way and that, and finally isolated the sound, but still didn't see any holes. So I started tugging on hoses to see if any were loose, and as soon as I touched that hose -- the one in your picture -- I felt the suction on my finger. The hole was in the back where I couldn't see it!

It was pretty much exactly the same hole in the same place. It's apparently a design flaw, and if so it probably happens a lot, so it's worth checking first, especially since it only takes about 5 seconds. It's the hose that runs from the PCV valve in the rear of the engine (I'm not sure if there's more than one) to the intake manifold collector. It's a short hose, about 7 inches long, 15 cm (3/8 in.) outside diameter, basically L-shaped.

https://cimg8.ibsrv.net/gimg/maxima....7e2feea500.jpg
https://cimg5.ibsrv.net/gimg/maxima....36ddabdf65.jpg

Thanks again and good luck everyone!

BTW as an alternative to the Nissan part you can use Gates brand part no. EMH296. It's available through O'Reilly; my local store was able to get it delivered to the store the same day for about $8.

I had the same problem. Crack in the hose, in the same exact spot. 2012 Maxima
https://cimg7.ibsrv.net/gimg/maxima....2f804f7c3a.jpg

https://cimg0.ibsrv.net/gimg/maxima....86e0714ae3.jpg

Thank you for sharing this info. I was able to determine I had the same issue. Appreciate the OEM part number share, too.

Thank you for sharing this and posting the pics! I was able to find out I have the same issue. Will see if O’Reilly can get the part quickly for me as well. Hopefully yours has held up for you.