O2 Sensors

Service Engine Soon light indicates an O2 Sensor problem according to Pep Boys. I just had one replaced about a month ago. My question is how many O2 Sensors are on a 99 with 5.7 engine and where are they? Is this an easy thing to replace yourself? Does the code readout tell you which sensor is giving the problem?

There are 4 sensors on that vehicle, two between the engine and the catalytic converters and two after the cats. The code should tell you bank ?, sensor ?. Bank 1 is the drivers side of the engine, and if you follow the exhaust from the drivers side of the engine towards the cat the first O2 sensor you come to is Bank 1 Sensor 1, and bank 2, Sensor 1 would be the closest one on the passenger side of the engines exhaust. The Sensor #2's will be post catalytic. Usually not too hard to replace except that some wiring connectors are near the top of the tranny sometimes and the post cat ones will sometimes be behind a heat shield

Thanks Jeremy! That helps a bunch...