Mitsubishi Repair: Oxygen Sensor Location, dual overhead cam, mitsubishi diamante

Question
I have a 2003 Mitsubishi Diamante 6 cylinder 3.4 Liter with dual overhead cam.  My service engine light and subsequent read out of the code indicates a failure of the oxygen sensor heater circuit Bank 2 Sensor 1.  I understand that my car has 4 oxygen sensors so I want to replace the correct one.  I believe Bank 2 indicates those sensors involved with the exhaust rather than the intake.  Is this correct and if so is sensor 1 before the catalytic converter or after it?  Will this be too difficult for a reasonably handy guy to replace?  I do my own brakes, oil, and most of the standard stuff.

Answer
All 4 of the sensors are in the exhaust. The "Bank 2" refers to the bank of the engine that does NOT contain #1 cylinder, in your case, #1 is rear bank against the firewall. "Bank 2" is therefor is the front against the radiator. The next part "Sensor 1" indicates that the sensor is located BEFORE the catalytic converter. If it said "Sensor 2" it would be the sensor after the catalytic converter on the exhaust pipe coming from Bank 2.  The sensor is up high on the exhaust and is easily replaced with a 7/8 wrench or if the heat shield is in the way, a oxygen sensor removal socket that has a cut-away to allow the wires to clear.  Use the antiseize that comes with the sensor and apply it to the threads to ensure it can be removed in the future.

Keep in mind that the code could be caused by wiring issues that are independent of the sensor harness itself, so replacing the sensor without actually verifying the correct/incorrect functionality of the device may lead to replacing a good component, although the cost likely makes it cheaper than having someone diagnose and then replace the sensor (as many techs just change the part as well).  

Good luck,  Kelly