I haven't changed my o2 sensor yet, but I have got the code reset twice just to double check what code was showing but every once in a while my check engine light will go off by itself and I was just curious to see why it would be going off by itself, it usually comes back on either shortly after the CEL goes off or when I start my car again.
Whats up with my upstream o2 sensor (I think bank 1) its throwing the P0135 code on 2011 Subaru Impreza WRX
by bobbywc in Bowling Green, KY on June 30, 2013
ANSWER by globalhelper on July 01, 2013
poss under your 8yr 80k emission warranty at the dealer