I got my front 02 sensor for $50 OEM Denso I highly doubt the rear O2 costs $400

 

Rear OEM is $300+. There's no reason to buy OEM that I'm aware of, but that it what it costs.

 

Where are you getting this information?

Here is the OEM Denso Sensor

https://www.amazon.com/Denso-234-428.../dp/B00122EE3E

 

OE style/equivalent is not the same as OEM.

https://www.extremepsi.com/store/pro...at=1060&page=2

https://www.maperformance.com/produc...on-ix-1588a119

Like I said, I don't see any reason the Denso one wouldn't be fine. Just clarifying that OEM is pricey.

 

Thats exactly the same thing, Denso is the one that supplies the "OEM" they can just slap that ridiculous price tag on their cause of three letters.

 

There could be a difference even if identical parts. The OEM part may be subject to a more stringent inspection procedure. Years ago I owned a DSM and the old saw back then concerning DSM owners was "Creating another generation of mechanics". This was because there was always something wrong with the vehicle. Well, the Evo has the same layout and the same engine but those problems are gone. What changed was the quality.

 

Still need help... I hooked up my car to modis scanner. Scanner shows rear 02 read between 110-300mv. When I test the 02 sensor wires it reads like it's suppose to rich to lean 100-900mv. I took it to Works and they checked out the tune(they tuned it) and they told me everything looks fine. I already passed smog, but would like this issue fixed as I might sell my evo.