Get a voltmeter and start probing your harness. There's most likely a wiring fault. If you don't know how or don't have the patience to learn, then go to yet a third and more competent mechanic that doesn't work for Honda. Get the proper diagnosis, and then have the 1st mechanic give you your old parts back and refund your money.

The o2 sensor is tied into many other sensors in your engine bay on the same circuits. Your TPS, IAT, coolant temp sensor, signals... I think there's another one. Your injectors and your o2 sensor share a common ground. I think your harness is damaged somewhere.