I always thought there were only 3 sensors....Front heated (right bank), Front heated (left bank) and another one on the B pipe...but after reading the FSM a bit, I am confused... can anyone confirm how many total there are?

I always thought there are 3. I got the following from the Haynes manual: "The upstream oxygen sensor is located in the exhaust pipe between the exhaust manifold and the catalytic convertor. The downstream oxygen sensor is located at the catalytic converter outlet." It doesn't say anything about the third oxygen sensor.

there's 3.

If you have Calif emissions, you have 4 of them. There are 2 'pre-cats' coming out of each cylinder bank, and there are sensors in front of and behind them.

He wouldn't have Cali spec living in Toronto, Ontario.

Definitely 3 of them.

3 for fed 4 for cali

unless he bought the car in or near cali, and brought it back home....

i have 5 o2 sensors..

some one has a wideband dont they

Only 99cali will have more O2's

here, take a look at this. it should answer your questions. it even comes with the dates. http://www.courtesyparts.com/A32_O2-sensors.html

damn, i need a new front bank o2 sensor, mines been out for a while now.

me, too, i hate my CEL. where's the best place to get them? is it oxygensensors.com or anywhere else?

I will have Front Heated o2 (left bank) and downstream o2 (from the B Pipe) off of a '98 GLE w/ 50k miles on them for sale soon.