O2 Sensor question
I think is still the biggest maker; the
GM one is more than likely Bosch inside.
Replace both sides. This will ensure they
are both similar in their response (though
the PCM appears to manage sides separately,
it's still best to replace them both since
as they age they do get sluggish and that's
seldom good for performance). Besides, the
incremental labor is like half an hour, once
you get it up in the air.

