2011 WRX Prem. This sensor was fine, but since placing it back into the collector after replacing my stock up-pipe, my car throws code P1153 after a half hour or so of driving. It's listed as an O2 sensor by some sites, and air/fuel on others, but I know it's the one the accessport reads air/fuel with. It seems to run, idle, etc, just fine, but then will suddenly peg to 20.8 AFR and throw a code, especially while cruising on the interstate. I found it for $109 on Amazon, and $103 on RockAuto, just wanted to see if anyone can find any better deals, or if anyone has had any experience with this issue and has fixed it without sensor replacement.
Here's a link to the one I found on amazon, it's Denso PN 234-9108 I think it's the right one, definitely trying to double check before I order a new one. Amazon.com: Denso 234-9108 Air Fuel Sensor: Automotive