CEL, P0171, help?

Yes, long term fuel trim is basically pinned at 39.8%. I did disconnect the 12v after I installed the new A/F sensor, but it nearly instantly shot right back up. Also, can you really push-start a Prius??

I decided not to invest any more time, cash, or energy into discovering what the exact cause of the problem is. I probably would, but the car is so rough around the edges now that I'm just planning to sell in the next few months and get a plug-in. I don't know if the economics can really justify that, but for various reasons I'll more than likely go for it anyway. Right now, the car's at 247k and gets about 38mpg on average. (That means that I'm paying about $9 more per thousand miles driven versus before the problem started.) Also, to say that the car's in Fair condition would be pretty charitable. If I can get the low end of the blue book range for it, I'll be very happy. On the plus side: the traction battery performs like new! Additionally, most of my paid work involves the car, so I can't really wait until it starts to become unreliable. Any opinions or comments are welcome.

 

Regarding putting in a new PCV valve, I had already done that (see post #15). As for putting in a new intake manifold gasket, yes I did do that but saw no change. Also cleaned the EGR piping and replaced one of the EGR pipe gaskets. Also replaced the throttle body gasket.

I also had MotorVac service done as a last ditch effort, figuring it couldn't hurt. No change, but I learned how important it is to fully trust your mechanic with jobs like that.

As noted in other recent threads here, the PIP premium is minimal to non-existent right now since it's typically more expensive to charge than to use fossiljuice. My 2010 had 59k on it when I paid $15k in 2012. Now I can get a 2012 PIP with 70k for $10k. I'm ready.