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!

 

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

 

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

 

Loose not really, but possible.

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