Any know if there are any ways, besides a costly trip to the stealership, to check/test if my o2 sensor has failed? My exhaust has smelled super rich and driving, for the most part, like a sane individual in the city netted me an 11.25 mpg average on my last tank of fuel. CEL used to come and go due to my AP cat delete pipe but it has been on solid for the past couple of weeks. Forgot the actual code but it says something along the lines of Bank 1 Sensor 2 low circuit entry. No idling problems but the car starts hard occasionally if i stop for gas or something after driving down the high way. Recently the car also does not seem to have a whole lot of power after I''ve been driving around for a while (3rd gear pull >6000rpm feels like trying to move from 40 in 6th).

2004 Manual 108k miles on original engine
-AP catback exhaust and cat delete
-re-medy water pump upgrade
-bhr ignition (10k miles on coils/plugs)
-OMP recently failed and was replaced

 

Get an OBD2 bluetooth adapter, download an OBD2 app for your smartphone that can run a mode test (Torque is the best for Android, not sure if free can do the test, but the $5 paid version is COMPLETELY worth the price). The Mode 6 test should give you a good indication of the performance of the O2 sensor

Bank 2 sensor is the rear O2 sensor, which seems to fail early on a catless rotary, and wouldn't produce those symptoms.

Get a compression test.