Cleaning O2 Sensor:

Remove sensor carefully (don't lose the metal washer, sometimes it sticks to the manifold)

Fill a glass jar or cup(don't use plastic!) with fuel injector cleaner to a level where it just covers the sensor housing (the part below the threads when the wiring harness is facing straight up). Dont submerge anything that isn't metal. Fuel injector cleaner can soften plastic.

Let it sit for 10 minutes.

Scrub with a stiff toothbrush or plastic detailing brush, making sure to push it into the holes.

Rinse with extremely hot high pressure water and then blow it clean with an air compressor. Be sure to remove all moisture.

Reinstall.

O2 sensors work by measuring resistance in exhaust gasses. Essentially all you're doing is cleaning electrical contacts.

I did this to both of the OEM O2 sensors on my 99 Acc 2.3 @ 160k (it was running rich, showing trouble codes for primary heated O2 sensor malfunction). Car runs smooth as silk and all trouble codes gone. 173K today. I drive 250-400 miles daily six days a week.