After I had my down pipe of my header replaced (where the 02 sensor resides) I got a check engine light and a code of 1 which is the O2 sensor. With an H23 you can buy the NTK replacement and the harness plugs right in. With the VTEC you get a universal NTK sensor and you must swap the harness from the old to the new sensor. The NTK is $53 shipped from Nopi vs. $200 for the Honda part.
Edit: the H23 OE replacement from Nopi should work in the H22 and it's just plug-n-play, no soldering.
Here's my tutorial:
Tools Needed:
22mm open end wrench
Needle nose pliers
Soldering iron and electrical tape (or heat shrink.)
Or Crimping tool
Step 1 Jack the front of the car up and put it on jack stands. Be careful, you're going to be working well back under the car, safety comes first!
Step 2 Disconnect the wiring harness. There are two clips and this can be kinda tricky. I used the needle nose on the smaller clip (sensor side) and my left hand on the large clip (carside.) With enough force it came free, just be careful not to tug on the wiring.
Step 3 Using the 22mm open end wrench loosen the sensor. Mine had recently been loosened and it still took a lot of force. I recommend balling up and old tee shirt to place over your knuckles. Once it let loose I skinned a couple knuckles. Now is a good time to make sure the sensor you bought fits!
Step 4 You want the finish length of the wiring to match the stock length. Basically you cut the wiring and solder it to the old harness. I recommend staggering the connections so you don't get a big bulge like I did. I highly recommend you solder over crimping. Here's the wiring chart:
Stock NTK Purpose
Green - Grey - Pos. Sense
White - Black - Neg. Sense
2 Black - 2 White - Heater
The heater wires can be wired either way, they have no polarity (it's a simple resistive heating element.)
Step 5 Reinstall the sensor being sure not to overtighten (spec is 25lb/ft.) Take your car for a test drive and hope you get no check engine light!
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