O2 sensor

I have a 2001 Silouhette (230,000 miles). I have an O2 sensor heater failure code, bank one, sensor one. This would seem to be the easiest of all the O2 sensors to access, but I can't find it. Can anyone help point me to the right location?

jack the front of the van up and put stands under the frame. Lay down under the van from the front side with you head towards the rear and look up. Just behind the engine and before the firewall is the sensor you want. Its hard to see but you can reach it from below. The other one is back near the converter.
John

follow the exhaust pipe up .undo the connector first then take the o2 sensor out .i ended up buying a set of lower ramps so i could drive the van up on them to keep from having to jack it up and put jack stands under it.most of the regular car ramps are too high and will not let you pull up on them.measure the bottom of your fascia on the front and get a set of ramps just a little lower than it . whole lot easier to just pull it up on them.