I have an error code of P0171 bank 1 sensor 1 too lean.

it's not the original engine, but i have attached some pictures of the error code reading, the engine (2.4l 16 valve DOHC) and the probable oxygen sensor.

So, is that the oxygen sensor for this error? It looks like it might be an easy fix because it looks like you're not replacing all the wiring as well, just unsnapping the wiring connection right on the top of the sensor, then replace the sensor. I can't tell what size of "star" screwdriver to remove those two "screws" though. looks like you take that thing off and unscrew the old one and put the new one in?

Oxygen Sensor on the manifold?