Is bank 1 o2 sensor in a 2002 Chrysler Sebring back of engine?

No, the Bank 1 oxygen sensor (O2 sensor) in a 2002 Chrysler Sebring is located on the exhaust manifold near the catalytic converter on the engine side closest to the passenger compartment (the front of the engine). "Bank 1" always refers to the cylinder bank containing cylinder #1. In most front-wheel-drive vehicles (like the Sebring), this will be the side of the engine closest to the passenger compartment.