2002 Pontiac Grand Am PO141 code retrieved

What is the mv on the o2 reading, should fluctuate between 350-550 mv, that will show if the 02 is working, if not Disconnect the HO2S 2 connector.
Connect a test lamp between the ignition 1 voltage circuit and a good ground. Turn the ign on tha probe that circuit with a test light. If it lights test the ignition 1 voltage circuit and the HO2S 2 heater low control circuit. Command the 02 heater on/off see if the test light lights, if it does it needs an 02 sensor. If you have a modis this should do bi directional tests like commanding the heater element on/off in the 02 sensor. If the test light doesnt light could be an open/high resistence or short to ground in the circuit. Post back with what you find.

These 02 sensors have a range 0f 0-1000 mv, it the range they operate in. You might have a heater element not functioning in the 02 sensor, the modis should be able to test this. Read the above post and test that 02 sensor the way I outlined. Post back with what you find.