Just thought I'd share what I found out about o2 sensors.

My 2000 Accord EX ULEV (the ULEV is important to note) had the Check
Engine Light come on.  Honda diagnosed it with codes P1166 and P1167
which could be due to a faulty O2 sensor or a faulty bung (where the O2
sensor connects on my DC Sports Header).  So I had them order a new
primary oxygen sensor for my car ($143).  After installing it nothing
changed.

It was only until I had the Honda service tech enter in my VIN that we
discovered the ULEV and SULEV models have different oxygen sensors with
different model numbers.  In fact the o2 sensor is made by Denso for
Acura. I was given part number 36531-PAA-L22  as the correct part for
an ULEV engine.  Honda wanted $175 for the part.

In comes the wallet saver Oxygensensors.com aka automedicsupply.com.
They had the correct oxygen sensor for my car Denso #234-9025,
confirmed the OEM part number on their site which replaces Acura
36531-PAA-L21, 36531-PAA-L22,  36531-PAA-L41  They sold it for $97.  I
also got their Sensor Wrench to install the O2 sensor. That worked like
a charm since the DC Sports header relocated the oxygen sensor
underneath the car and on top of the down pipe.

If you have a CEL with error code 1167 make sure you have the Honda
dealer enter your VIN number to check for part numbers otherwise you
may not get the right part.