Cadillac Repair: 97 Eldorado is running rough and the serviceengine light is on., climate control, o2 sensor

Question
My 97 eldorado is running very rough and the service engine light is on and was blinking and now is constant, could this be the O2 sensor and if so where is it located so I can change it out or do you have any other suggestions as to what it may be?

Answer
Check the computers for codes via;

1. Ignition ON, Engine OFF.

2. Simultaneously push and hold the OFF and WARMER buttons on your climate control panel for 3 seconds and then release them.

3. CODES will appear on the fuel data display in the form of LETTERS and NUMBERS (ex: PC0441 or some other combination of letters and numbers). Also after each code appaers will be the word CURRENT or HISTORY.

4. tell me EXACTLY what displays as if you were video taping the display.

5. Turn ignition OFF.