fredflypogger

hi
i have "service engine soon" on my 2000 maxima,i went to autozone and
it scanned a p0171. does any one know what this means?? the car is running fine it has 63k miles. any help would be aprreciated.
thanks
todd

itdood

this is what it means: "P0171 System too Lean (Bank 1)"

What that implicates is beyond me. Good luck!

sloppymax

iTrader: (8)

sounds like a bad injector on the right bank. its running lean so im assuming the injector's cycle has been significantly decreased.

DanL

It's usually one of four things -- an air leak around the intake, a failing upstream O2 sensor (usually accompanied with other O2-related codes but not always), a failing injector, or a failing MAF sensor.

[maxi-overdose]

iTrader: (3)

lean = too much air, not enough fuel

per FSM:
possible cause of P0171
-intake air leaks
-heat O2 sensor
-injectors
-exhuast gas leaks
-incorrect fuel pressure
-lack of fuel
-MAF

spirilis

iTrader: (2)

Don't discount a fuel system problem... e.g. horribly restricted fuel filter? (or weak fuel pump, though I'd assume the fuel filter would cause problems before the fuel pump would)

fredflypogger

hi,
thanks for the quick response. i will check all of those areas.
thanks again
todd

[maxi-overdose]

iTrader: (3)

hard to say. my car was running super super lean with the SC for 1000 miles because the inline fuel pump (additional pump) was off. It was a super lean 20:1 AFR but this code was never never triggered.

So this code is applied to close loop operation only and it is picked up the O2 sensor. Since he only sees it in one bank and that means the O2 sensor reading in other bank is still ok. It shouldnt be caused by inadquate fuel pressure (dirty fuel filter/weak pump).

another symptom of clogged fuel filter or bad pump is rough idle. But you have to use a fuel pressure gauge to i.d. the problem. It is hard to attach a fuel pressure gauge before the fuel rail on 2k-2k1. You will have to release the fuel pressure first and disconnect the fitting near the firewall.

try to disconnect the battery first and see if the code comes back


good luck.

phantomax01

i know this is a dumb question but, i dont understand how people find out if they have an error code how does it work, you go to somewhere like autozone and ask them if youre car has trouble??

[maxi-overdose]

iTrader: (3)

is your check engine light (aka service engine soon) on? if so, that means the ECU picked up 2 consecutive codes from on of her sensors and you can pull the code.

some codes will not trigger the CEL, i.e. knock sensor code.

DanL

Autozone will hook up a hand-held OBD-II scan tool to your car's ECU via a connector located under your steering wheel. The scan tool will read the error codes stored in your car's ECU and you can look up those codes to see what the symptoms are and help diagnose the problem. Takes all of two minutes to do and Autozone (most at least) will do it as a free service. The dealer can do the same but will charge around $85. You can also purchase your own scan tool, either a portable one like Autozone uses or a hardware/software version that can be loaded on a laptop or PDA. The cost is around $120-$160. BTW, the laptop/PDA versions are far superior and let you do a lot more than just read and clear codes.

bobby.cim

HEy fredflypogger, was wonderin if u fixed the problem with the P0171 code? I have the exact same problem, not sure if I should buy and replace the O2 sensor

SkylineGTR

I'll bet you any amount of money that it is the MAF. I had this same exact engine code come up, and the shop I had look at it, swore it was an intake manifold leak, or a bad injector. God forbid they check the simple **** first.

Replace the MAF in a very timely manner, as soon as possible if you can. 2000-2001 Maximas aren't notorious for injector problems or O2 sensor failure. Most common problems relate to the MAF and/or coilpacks.

In my particular case, I was observing powerloss throughout the powerband, most noticeable from 3500-6500(redline). Soon afterwards I got that same exact engine code, p0171. That was later followed by a Cylinder 3 Misfire, and the number 3 coilpack eventually crapped out, and the engine was running on 5 cylinders. Everything is running fine now, but because number 5 was still getting fuel, and not burning it, it built up some nasty deposits on the O2 sensor on that bank.

Go get a replacement MAF, and replace it soon before other problems start to add up.

TK

bobby.cim

How much does a MAF go for and can i install it myself?
Is it definitely not the O2 sensor? Or do I have to replace that also? I've had my light go on and off for a few months now and still only says P0171.

SkylineGTR

70-90 bucks, depending where, you get it. Even so, it's not a bad part to have an extra functioning one just laying around.

TK

bobby.cim

I researched MAF failures and they all say that your revs should not go higher than 3K. I have a lack of power but my I have no problem goin past 3K

bobby.cim

well i bought a MAF after talkin to Dave B bout it. I'll find out soon if thats the prob

SkylineGTR

It's actually 2500rpm, but if your MAF is still within voltage range, it won't throw a code. Trust me, I listened to 'everyone' who said that MAF is only bad if you can't rev past 2500 rpm, and it took a LONG time to figure out that the MAF was the problem.

TK