Good Day.
Short Story:
I had a bad O2 sensor.
I replaced it with a new Denso from Amazon. I took it to AutoZone to clear the CEL.
CEL came one one day later. The CEL is Bank1 Sensor1.
I did a ECU reset by warming up the car, turned off car, disconnected negative, and pulled various fuses. Started car, let it warm up and NO CEL.

One day later CEL came back on, what gives?
Stock Headers.
Air Fuel Ratio looks good based off the readings from my wideband.

 

Have you hooked a scanner to it to see what voltage the O2 sensor is relaying to the ECU? It might not be within spec like the OEM O2 sensor.

 

like a CEL scanner? Will it detect that? Or do you mean multimeter?
I tried to measure an o2 sensor for a past problem but I could not figure it out..

 

Is this the part number you used: 234-9041? I got it from densoproducts.com. Also, referring to the scanner, I mean a diagnostics tool you plug into the OBD-II port and see in real time what the O2 sensor is doing. You can then take what you see on the graph and find what the "range" of voltage the Bank 1 Sensor 1 range is supposed to be from the factory.

 

Delivery Estimate: Wednesday May 9, 2012

Denso 234-9041 Oxygen Sensor (Air and Fuel Ratio Sensor)
Sold by: Car Parts Warehouse, Inc. ( seller profile )

I'll try to find a shop with a fancy scanner. I only encountered typical engine code checkers.
My car runs pretty good, but Damn in 5 years I haven't had a CEL.

Edit: I'll check the box if I still have it in the garage (I probly dont...)
Edit 2: can I find the part number on the sensor itself to confirm? The threading is fine and the connector fits just right...

 

You didn't touch the sensor's tip at all when you put it on did you?

 

I want to be so sarcastic right now. Yea my GF gave it a BJ right before I put it in.
But seriously I went in smooth and I didnt touch it. Nore do I think anti-sieze got all over it either. Car still drives smooth as hell tho.
But I heard Bank One Sensor One can also be cause by a vac leak, I'll double check that. There is a rubber hose that plugs into the top left of the valve cover that is in need of replacement.

Otherwise i'll have to find a shop with a hardcore OBD-II computer.

 

Honestly you need to go with your OEM O2! Trust me, you might've wanted to save some money, but these generic parts don't have the same specs as your OEM, because yeah the readings may be similar but your PCM Has set conditions it needs to see. But anyways, try going with OEM if your not modifying your car.