P0171

Well, I don't have p0171 any longer. Driven for 150 miles. Car drives smooth. Mpg is 45mpg 2-3mpg better after I replaced CAT. Valve cover gasket was replaced 6 months ago. As expected of high mileage Prius I top off oil (1 quart) between oil changes. There are no visible oil leaks.
The bolt of the part below the maf was loose (maybe when I went there to replace MAF..bcoz i got p0171 right after). That's what the mechanic said and I think that was why I was getting p0171

 

Interesting 2 years no p,0171. Now got it again on a 110F day. The previous time I had it was also on a hot summer day .

It's most definitely not a MAF sensor issue as I replaced it. Mechanic had also ruled out vacuum leak after smoke test Just clueless why all of a sudden on a hot day p0171 comes back after literally 2 years of no such code. Last time mechanic had said he had tightened some bolts near the air intake and then after that I had no p0171 for 2 years.

Any ideas? I have reset it and driven 10 miles...so far no code & engine running smooth

 

So you're in Nevada with full emissions testing you have annual inspection?

 

Yes. Emission test passed a month ago.
Why

 

I was just curious if you were under that kind of a gun I don't have emissions testing where I am so I can ride around the check engine light on for 5 years as long as it's not affecting my gas mileage in my personal finances no problem. Where you is not sooo much. Certainly interesting how it seems to corelate w heat

 

Replaced it with OEM or some aftermarket? What brand, if aftermarket?

What are your fuel trim readings for long and short-term fuel trims?