There are several things that can cause this trouble
code. First let's be sure that you replaced the
correct oxygen sensor. You're looking at bank 1
sensor 1. This is the oxygen sensor before the
catalytic converter on the side of the engine where
the number one cylinder is. The resistance of the
oxygen sensor should be around 8 ohms. If that's
good, do you have an exhaust leak ahead of the
oxygen sensor? You might have a vacuum leak or
even low fuel pressure. If your current mechanic
can't diagnose the problem you should take it to
someone else who can. Since the check engine light
keeps coming on and setting the same trouble code
the problem has not been fixed. Hope that helps!
Jim