The check engine light just came on today in my 96' Maxima, and when I pulled the codes, they were 0503 and 0303 (right and left bank O2 circuit faults). The car has just under 100K miles. What are the odds they both went bad at the same time? I installed a budget Y-pipe about three months ago, but the car has been fine (no codes) since. Are the two O2 sensors on the same circuit? Could it be a bad wire? It's a Ca. car, so I don't think moisture or a ground would be an issue. Any insight / ideas would be appreciated ! Thanks.[FONT=Arial]

 

I wouldn't be surprised if they both went out; 100K is about where they go if they hadn't already. They're very easy to replace so order them online at www.oxygensensors.com

~THT