PO133 Code - Which O2 Sensor?

I've had a sporadic SES light, Autozone read it as a PO133 code which
relates to the O2 sensor, my question is, they have two O2 sensors
listed, one pre-cat converter and one post. Any thought as to which
O2 sensor this code relates to? The car is running fine and has
passed smog recently (thankfully the SES light stayed off through the
test...) but I'm thinking I should take care of it eventually.

Jeff

 

P0133 is sensor 1, the pre-catalyst sensor.

 

Hey Jeff,

According to Haynes book, P0133 code is "Upstream heated O2 sensor circuit
high voltage (Bank 1 Sensor 1)

Best I could find. Good luck.
marx404

 

Thanks to all that responded. A follow-up question, anyone know the
real difference the $22.99 Borg Warner I got at Kragen and the ones
that cost 3-4 times as much? I had to cut the old wire and re-use the
wiring harness, but I figured at this cost even if it doesn't last
quite as long I could replace this three times for the price of one of
the others? In any case, it's done the trick and no more SES light.

Jeff

 

Probbably the box it came in. IIRC, almost all O2 sensors are Bosch or
NTK (???)