speedAD'ic

the car is a 2002 with 14500 miles on it. what would cause the O2s to go bad,i take them out and there total black! its done this twice now, what happens is it will only read lean and that casues the injectors to dump fuel in making the cars check light go on and run really rich ! . i cant figure it out once i put a new o2 in the car reads fine and goes back to normal?? ~ i dont use any fuel additaves and i dont spray so i dont know ?
Please halp

Colonel

Exhaust leak.
Open headers without extension tubes.
Coolant coming into contact with them.

Moving to External Engine... <img border="0" alt="[Burnout]" title="" src="graemlins/burnout.gif" />

<small>[ October 20, 2002, 07:43 PM: Message edited by: Colonel ]</small>