How i solved my P0171 code
 

Hello!

So made this account just to help people whenever i get a chance.

The car is a 2003 Lexus ES300

I'm a honda guy who just decided to get a Lexus and just so happen to get a check engine light like 7 months after. I see a lot of guys still having problems identifying which sensor or leak is causing the now famous P0171. So after i got the mil, decided to track it down and the scanner was giving me like 5 or 6 different codes, all related. Everything pointing towards bank 1 being too lean. So i did almost everything known trick on the cheap side of things such as vacuum hose, clean maf, replaced pcv, and replaced a vacuum switch valve that broke as i was removing the hose (it was toasted). So today i went at it again with the engine running and started pushing and pulling things until i pulled at the flex tube right after the MAF and heard the idle change so to make a long story short, that one tube had a long crack so i removed the part, and put a piece of 3M electrical tape just to check and problem fixed.

Btw, I had to reset the ecu to get it to clear.


I just hope somebody can use this before buying new MAF or Air Fuel Ratio sensor. Mine cleared 5 different codes, i just decided to go with the one on top of the list P0171.

Also my MPG went from around 22.4 to 25.

Fantastic. Thanks for sharing.

Had same problem and also figured it out on my own when looking for vacuum leak. Mine was basically totally broken off. I hope more people find this answer. I'm sure it's a common cause for this problem, and thankfully a cheap fix. Can get a brand new tube on ebay for about 16$