Which oxygen sensor goes bad first and if it's a little off does the check engine light show this?

I have 88,000 miles on my car with stock sensors and my car is starting to drink fuel like crazy, I changed alot of stuff but i think it's the O2 Sensor.

Also does anyone know where to get these for cheap?

 

yes i need to replace mine too. getting codes 0901 and 0902. 0902 is undefined?

 

Yeah, same here, i have had 0901 for maybe 2 weeks, and it went away...but the bulb isnt blown- so i can assume the ECU isnt found no more problems .

0901 is Upstream oxygen sensor heater fault (right bank)
0902 is Downstream oxygen senosr heater of circuit fault.

That should help a littel for you 98fivespeed....

 

Just in case anyone needs it. I have a front 02 sensor for sale. Brand new OEM o2 sensore. $90 shipped. It retails for over $120 at the dealer