Ok. So I have read everything I can find on the internet about these two codes, mostly from my350z and am left with just about nothing. I am hoping there is someone here that has had these exact two codes come up and figured out exactly what it was.

I have read that they can be caused by a list of things from an intake leak to fuel pressure issues but what I am trying to avoid is going into a shop and having them try to do what the nissan dealership here did and charge me 800 dollars to replace my two top o2 sensors.

The actual code reads:

P2A00 - O2 Sensor Circuit Range/Performance Bank 1 Sensor 1
P2A03 - O2 Sensor Circuit Range/Performance Bank 2 Sensor 1

I have a 5/16 MD Plenum Spacer ( Checked for leaks ) And had test pipes but put my stock cats back on and bought brand new OEM Rear O2 sensors when I put my cats back on since the shop that took out my Old O2s stripped them. I have never touched my headers or the O2 sensors going into them so I find it unlikely that they would both fail at the exact same time.

If anyone can at least help eliminate some of the least likely causes I would greatly appreciate it! I am deploying soon and don't want to try and sell my car with a SES light haha.

Oh btw it's an 06 Coupe. Thanks in advance!