So I replaced my upstream O2 sensors about 2 years ago and about a month or two ago I got the P0135 code (bank 1, sensor 1). I replaced the bad O2 sensor and the code went away. Fast forward to yesterday and the P0135 code came back on... WTF? Is it really possible that my O2 sensor went bad already??? Is there a way to test them to see if they are working so I can decide if it is an issue w/ the car or an issue with the O2 sensor?
Thanks erebody
Thanks erebody