Just to let people know when they do a search for these codes to see whats wrong with their car...I just had an easy fix for both of these codes...first off the P0057 code which is bank 2 oxy sensor 2..the one in drivers side catalytic convertor...just replaced it, thnking that would cure the code, but no, kept coming up-along with the p0171...figured the 57 code was why the 171 code of running lean bank one, but not yet.....anyway the 57 code was due to the connector where the o2 sensor plugs into harness was backing out just a touch-had to put zip tie to pull it together.....cured that code

Then the p0171 code was still coming up, so did a search and sprayed carb cleaner all over motor,power brake booster and all...nothing...then I noticed the pvc hose was all wet with oily residue...went to take it off(hard as a rock), and it spun real easy on nipple coming off the intake manifold-turns out it was split underneath where you could not see it and carb cleaner did not get to it....replaced the hose...and voila! cured that code too...gas mileage went up a couple miles per gallon too..I was at 16, now about 19!! still not 30 like I want, but hey i do drive it fairly hard, and sort of fast...so I guess any improvement is good....

Awesome info! I had a broken hose off of my PCV valve once and it caused similar issues. Thing was so brittle! Tough to replace, being way down in my engine, but I'm glad it's done and over with. Thanks for sharing!