Ok guys, a week ago or so i posted about my truck throwing the p0172 and p0175 "too rich" codes. As basic maintenance and also to maybe correct the issues, i replaced my (original GM) air filter. Now, I'm getting p0171 and p0174 too lean! Could it have been not sucking enough air and have had a fuel blockage? I didn't notice any crazy power gains after the air filter, but now I'm guessing it's a fuel filter? I have yet to test my fuel pressure but i"m assuming if the air filter was stock at 155k, so is the fuel filter. Any other ideas? Thanks!

 

Did you clean the mass airflow sensor? Clear codes first see if it comes back.
Are you having any hesitations , missing ect. ?

 

What year is the truck? engine size?

 

Sorry, forgot to mention that. It's a 97 k1500 5.7 vortec. I took the MAF off, but it was sparkly clean to the eye. Is it still worth a cleaning? Also, I cleared the codes after the air filter, so they came back after that. Also, no problems whatsoever with hesitation missing. Thanks for the replies!

 

When was the last time you changed the fuel filter? Does the truck seem to run normal?

 

The truck runs fine, nice smooth idle (650ish) and no bogs/hesitation etc. I just got the truck so I don't know about the fuel filter. I'll probably do that even though it's too rich

 

I would clear codes ... go from there if it is running fine.