Bank 1, bank2 ???

I failed my emission test and they told me I have a bad O2 sensor in bank 2. Which is bank 2? Front of engine (easy to replace) or rear of engine (hard to replace). I bet I already know the answer.
Thanks for the help,
Don

Bank 2 is at the left front of the engine. Bank 2 has only 1 sensor, at the front of the exhaust manifold.

Bank 1 Has 3 sensors, 1 at rear of exhaust manifold & 1 ea. at pre & post converter locations.

Bank 2 is at the left front of the engine. Bank 2 has only 1 sensor, at the front of the exhaust manifold.

Bank 1 Has 3 sensors, 1 at rear of exhaust manifold & 1 ea. at pre & post converter locations.


Thanks.......................I was able to replace the O2 sensor at the front left with little to no change in rough running. I tried to get to the other sensor at the rear middle of the engine but could not remove it. I can only get a wrentch on one way and I was unable to get enough leverage on it it to remove it. The manual says I have to drop the engine/tranny mount brackets 3 inches to change it and I unfortunately don't have all the necessary tools to do that. I'm gonna have to bite the bullit and take it to a mechanic.

The pre and post cat sensors look to be an easy change.

Thanks for the help.
Don

My engine was running rough & it turned out to be the pre cat sensor. Easy change. Autozone read the code, which identifed that sensor. Sensor was about $50 & solved my problem.