My CEL turned on last night and it said 7,7. This means: Rear Heated O2 sensor. How vital to running effiencietly is this O2 sensor and how much would it cost to repair this....if I got a y-pipe would I have to toggle anything with the O2 sensor? Any advice is much appreciated!

-Lieb-

 

Very vital. You'll get crappy gas milage...and that's just one of many sysmptoms. I believe I paid like 120 for my O2 sensor. Try search.