2007 Tahoe 5.3 - O2 codes still exist after replacement

[Thuhreb]

Looking for some help here folks...
2007 Tahoe LT 5.3

I'm throwing codes
P0053 (detected a malfunction in the heater circuit of the upstream)
and
P0134 (problem with the oxygen sensor that is positioned before the catalytic converter and on the engine bank that houses cylinder #1)

But I've already replaced sensor, cleared codes, and checked fuses #8 and #18 in the fuse box in the engine bay. Those look good. I'm still getting these codes shown. The O2 sensor I replaced was the one before the catalytic converter on the driver's side. From what I researched, that would be the one to replace with these considering these codes.

Where do I go from here? Thanks in advance!

 

[swathdiver]

It is not your O2 sensor that is faulty, it is the wiring going to the connector, specifically the one that controls the heating. Get yourself a wiring diagram and or get underneath and check your wiring for damage. Driver's side, upper sensor wiring.