P0136 ho2s-12 Mazda Tribute
 

Hey all,
I have an 02 Mazda Tribute with over 200k miles on it. Its been very reliable. Check engine light indicates the error p0136. I get what the issue is but where the heck is the sensor? If bank one is towards the firewall, I don't see any sensor sticking out of the exhaust. There is an obvious one on the other side under the front bumper. Someone said to me; that's the one but isn't that Bank 2?

The car barely idles, sounds like its misfiring. I'm worried it someone more then this sensor. I admit the check engine has been on awhile before I had it looked at. The car has been running fine until today.
I'm no mechanic btw. I understand the basics. Thanks for any help.
- Chris