my 03 2V 5.4 tripped a CEL yesterday. i got the codes ran today, PO 172 and PO 175. if i am understanding correctly, i am running lean. my observations seem to confirm this, as i am suddenly getting significantly more miles per tank. where are the best places to start to fix this issue? i performed a search, and one other thread had the same codes. from this thread, i gleaned:

1.) bad o2 sensors (how do you test them?)
2.) dirty MAF/air filter/throttle body
3.) bad COP's (again, how do you test)

which is the best to start at? i'm thinking new air filter, and clean MAF/ TB. or, should i start elsewhere? keep in mind this engine has 46k miles on it, and has seen minimal maintenance up unto this point, aside fluid/filter changes. thank you all for your help.

 

i thought those are rich codes....

P0172 bank 1 too rich
P0175 bank 2 too rich

i doubt that both front 02 sensors crapped out at the same time. I would clean TB, MAF, and unplug the battery for about 2 hours (while you do the cleaning work) and let the computer reset its adaptions

 

i could be wrong, that's just what i thought. thanks for the tips, patman.

 

yep its too rich. do you have a wideband?

 

no, i do not unfortunately. i just opened the hood, and to my shock, the air filter had been dislodged off the intake. i'm assuming this could have very likely tripped the codes. hopefully, i didn't damage anything driving around like that. it has only been less than 50 miles since the codes tripped. i'm still gonna pull the TB and clean it, as well as the MAF.

 

yea you didnt hurt anything.

 

well, after cleaning and reinstalling the filter, and disconnecting/reconnecting the battery this morning the codes/CEL went away. thanks, guys.

 

Just for future reference, lean/rich codes tell you that if anything, the O2 sensors are working. 99.9999% of the time, when you have a rich or lean code, it's not an O2 sensor.