Just got done replacing both downstream O2 sensors in my '07 Silverado 1500 today. As I was working ont it, I got to thinking... Can afterfire cause O2 sensors to go out?

When I'm towing a loaded trailer or coasting down a hill, I sometimes downshift a gear or two to save my brakes when slowing down. When I do this, the exaust will often pop and crackle loudly as the idling engine pulls my speed down (I have cat-back x-pipe dual straight pipes and a modular intake, so arguably it sounds freaking amazing, but that's besides the point ). The engine and trans have always seemed to be perfectly fine with this, but I still wonder if it shortens the life of the O2 sensors?