2000 4Runner Limited check engine light
 

Hey all, I'm new to the site. I have 2000 4Runner with the check engine light on. First of all, the truck has CA emissions. I am getting a code PO 171, lean in bank 1. I have replaced the O2 sensor, cleaned (not replaced) the MAF sensor, and seafoamed the gas tank. The engine light is still on, showing the same PO 171 code. I have also taken it into Toyota and had the 90k-120k mile maintenance done, including replacing the timing belt and water pump. I was wondering what else I can do to fix the problem. I also had to replace the muffler about eight months before the check engine light came on, but the guy got the wrong muffler, supposedly it was bigger and better than a stock one. I don't suppose this muffler, not being a stock muffler, could cause that code to come up as well? Any help with this would be greatly appreciated. Thanks!

RE: 2000 4Runner Limited check engine light
 

The muffler just being aftermarket isnt the problem, perhaps look under and around to see if he popped something off when doing it.

RE: 2000 4Runner Limited check engine light
 

But would something being loose cause the check engine light to remain on?

RE: 2000 4Runner Limited check engine light
 

Loose not really, but possible.

If something came disconnected as I mentioned it would/could be a hard code.