How do you replace Oxygen Sensors for Jeep Cherokee 1999. I have no idea where are they located or how many new oxygen sensor do i need... will be super nice if someone answer with pictures. Thanks.?

it would be easiest to get a O2 sensor socket to remove it, they are located on the exhaust pipe itself, not far at all past the engine, i cant tell you how many you need but if you look and count them that would tell you that (if you cant get a O2 socket you could get it with a wrench, or sometimes a regular deep socket)