Originally Posted by midiwall

A breakout of the codes is here:
https://www.yotatech.com/~corey/tech/dr_z_obd/dr_z.htm

From there, a P0171 is "system too lean, bank 1". "Bank 1" defines that this code is coming from the O2 sensor that's in front of the catalytic converter. (a similar code, P0174, would point to the O2 sensor after the cat) And yes, the O2 sensor is what the engine computer ("ECU") uses to compute the Air/Fuel Ratio.

There are a slew of codes (P0130 - P0167) that point to issues with the sensor itself, so that's not the place to start. I would guess that the sensor is "fine", though it may not be 100% perfect.


Anyway, what you've been told thus far is good info... The place to start here is with the MAF. The cleaning process is easy, and well documented here:
http://www.4x4wire.com/toyota/maint...ntenancep5.html

Past that, the air filter should also be replaced (or cleaned if it's a foam unit).

Try those two things first before replacing the O2 sensor, it's a fairly expensive part ($90) that will turn into a $160 visit to the dealer (parts plus labor).


Oh, you also asked for a favorite online parts dealer...

I've had great luck with these guys:
https://www.1sttoyotaparts.com/partscat.html

But, if you're thinking O2 sensor, then the best prices around are coming from a performance specialist ("Gadget") at URD USA:
http://www.urdusa.com/

Originally Posted by 3.4v6

well i just cleaned the MAF and it did look a little bit dirty , next i think im going to ditch the k&n drop in filter and get something else. i just got the o2 sensor replaced about 6 months ago due to warranty issues so i hope that isnt it.

Originally Posted by FilthyRich

FWIW, I am not sure why, but my old K&N drop in caused CELs quite a bit. I have since replaced it with an Amsoil and have not had any problems.