This code has been coming and going for a few weeks now, I've seen it 3 times. It says bank 1 sensor 2, are there 2 02s on this? (99 ls 3100) If there are, I'm assuming 1 pre-cat 1 post cat, and sensor 2 would be post cat? Reason why I'm troubled is because my Lincoln has 2 02s, both before cats, the 96 and newer lincolns had pre and post cats, but the post cats were unmonitored and couldnt trigger a cel. Anyway, the 02s are going bad, 171k on the car and I still get 20mpg, but I do realize that not changing the 02s will further complicate things, so does anyone have an underbody shot of where they are located, any tips, etc. How hard of a job is it? On the lincoln its dreaded because there is no room.

 

Your car has 1 pre and 1 post cat O2 sensor. The post sensor is located right at the converter outlet and is fairly easy to get at. There are 4 wires going to the post O2 sensor. The pink wire supplies voltage for the O2 heater and the black wire supplies the ground. Before replacing the sensor make sure you have battery voltage on the pink wire with the key in the on position and a good ground path on the black wire.Its easy to check these circuits at the postO2 harness connector.You can also check the heater itself by connecting an ohm meter to the heater circuit terminals on the sensor connector. The resistance through the heater should be 5-6 ohms.