# Obd code p0171 **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** nissan, code, altima\ **Created:** [March 14, 2011, 12:39pm UTC](https://community.cartalk.com/t/obd-code-p0171/62597 "2011-03-14T12:39:50Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![gmendiola](https://avatars.discourse-cdn.com/v4/letter/g/a698b9/32.png) [@gmendiola](https://community.cartalk.com/u/gmendiola)\ **Post date:** [March 14, 2011, 12:39pm UTC](https://community.cartalk.com/t/obd-code-p0171/62597/1 "2011-03-14T12:39:50Z")
This code keeps coming up on my OBD reader can someone, can you point me in the right deriction as far as what to look for to repair this code. I read on this other forum that it could be vacuum leaks etc., ---
**Author:** ![cigroller](https://avatars.discourse-cdn.com/v4/letter/c/c68b51/32.png) [@cigroller](https://community.cartalk.com/u/cigroller)\ **Post date:** [March 14, 2011, 12:43pm UTC](https://community.cartalk.com/t/obd-code-p0171/62597/2 "2011-03-14T12:43:15Z")
This is a pretty good summary including what to look at: [http://www.obd-codes.com/p0171](http://www.obd-codes.com/p0171) The only thing it doesn’t say is that if you eliminate all other possible causes then the upstream O2 sensor might be faulty. But you have to eliminate the other causes first. ---
**Author:** ![aanders999](https://avatars.discourse-cdn.com/v4/letter/a/8dc957/32.png) [@aanders999](https://community.cartalk.com/u/aanders999)\ **Post date:** [March 14, 2011, 10:54pm UTC](https://community.cartalk.com/t/obd-code-p0171/62597/3 "2011-03-14T22:54:42Z")
On my 1996 Ford Crown Vic I have eliminated this code a couple of times by cleaning the MAF. They sell aspecial cleaner in auto parts stores and the clerk will be able to show you where it is located in your car, in the air intake snorkle…Andy ---
**Author:** ![castironman](https://avatars.discourse-cdn.com/v4/letter/c/2acd7d/32.png) [@castironman](https://community.cartalk.com/u/castironman)\ **Post date:** [March 15, 2011, 12:42am UTC](https://community.cartalk.com/t/obd-code-p0171/62597/4 "2011-03-15T00:42:26Z")
Please post year, motor and mileage, as well as sub model if applicable. Basically, this code means that a lean condition is present and the fuel trim corrections were unable to correct it without degrading emission restrictive parameters. There is too much Oxygen at the oxygen sensor(s) (depending on mileage may be time to replace it - could be reading wrong…), which could be caused by a dirty MAF, a vacuum leak after the MAF (cut on the rubber or leaking hose - PVC for example ), faulty EGR system, faulty fuel pump, faulty fuel filter or pressure regulator. Do you have also a misfire code there ? ---
**Author:** ![JoeMario](https://avatars.discourse-cdn.com/v4/letter/j/3bc359/32.png) [@JoeMario](https://community.cartalk.com/u/JoeMario)\ **Post date:** [March 15, 2011, 1:29am UTC](https://community.cartalk.com/t/obd-code-p0171/62597/5 "2011-03-15T01:29:15Z")
I doubt this is your problem, but I share it as an fyi. When I had a P0171 on my Hyundai Sonata, it turned out to be a rodent had nested in the air filter box, had chewed the air filter to bits and made a nest. When the car started, all the air filter pieces got sucked up into the inlet screen on the intake - triggering the code. ---
**Author:** ![cigroller](https://avatars.discourse-cdn.com/v4/letter/c/c68b51/32.png) [@cigroller](https://community.cartalk.com/u/cigroller)\ **Post date:** [March 15, 2011, 1:53am UTC](https://community.cartalk.com/t/obd-code-p0171/62597/6 "2011-03-15T01:53:20Z")
I’ll bet you that’s not too uncommon. I have to wonder - between chewing wires & chewing various points in the air inlet- how many innocent oxygen sensors have been needlessly sent to the trash by rodents? I can’t imagine we’ll ever know. ---
**Author:** ![gmendiola](https://avatars.discourse-cdn.com/v4/letter/g/a698b9/32.png) [@gmendiola](https://community.cartalk.com/u/gmendiola)\ **Post date:** [March 16, 2011, 4:35am UTC](https://community.cartalk.com/t/obd-code-p0171/62597/7 "2011-03-16T04:35:19Z")
2000 Nissan Altima 4cylinder 152,211. There are is a hose that looks to be missing a connection, as well as this other part that appears to be missing a hose coming from the air filter like next to it is a sensor. See pix ---
**Author:** ![Honda-Blackbird](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/honda-blackbird/32/3159_2.png) [@Honda-Blackbird](https://community.cartalk.com/u/Honda-Blackbird)\ **Post date:** [March 16, 2011, 4:39am UTC](https://community.cartalk.com/t/obd-code-p0171/62597/8 "2011-03-16T04:39:13Z")
System too lean…usually caused by dirty MAF…remove MAF and spray clean with apropriate cleaner…either brake cleaner, carb and choke cleaner or MAF cleaner spray.