hi all,

i have a late 99 silverado 5.3 with 175,xxx miles. just today, i got all three codes....

P0171: Oxygen sensor system too lean fault bank A
P0446: Evaporative emission system vent control circuit
P0453: fuel tank pressure sensor high out of range fault

P0171------- so, i have a lean o2 sensor, but im hoping its not the intake manifold gasket (i know this is common on this motor) because from what i read if it were the IMF it would give me both bank o2 lean codes??

P0446-------- purge solenoid? no clue, just been youtubing....

P0453-------- fuel tank pressure sensor obviously???

like i said they all came up together, today, so i'd assume they are related.

but with all the fuel talk (codes), i must note within the past 6 months or so my gas mileage has gone from 15-17 to 12ish mpg.

also, 4 years ago, a somehwhat newbie (then) mechanic replaced my fuel pump. it has worked fine ever since, but after he did it my fuel gauge would be all over the place, randomely moving, then it would either be on Empty or Full. for the past year or so its been stuck on Empty (very annoying, fuel light always on), and very recently it started going between Empty and 1/4..... very odd.... not an issue, as i just use the trip meter, but ya....

and lastly ill note that my engine light went on last weekend and when i hit the highway on my way home to scan it, it went off..

thanks in advance!!

 

bump 12345

 

Did you ever find out the issue??

I just got a P0446, too... and I'm doing a bit of research.

I did read where the evap canister uses vacuum to clear the fuel vapors into the air intake...you are getting a "too lean" fault, too...maybe look at a vacuum leak?

 

i cleared the code and its been out ever since (over 2 months)