2000 dodge intrepid 3.2 engine light on yesterday, code PO432, should I replace the upper oxygen sensor?

First take no advice from the kids at Autozone, they have no training. as for the code here are the most common reasons for the code you have.
Possible causes - Warm Up Three Way Catalytic converter deterioration or malfunction
- Exhaust system leaks
- Loose front or rear HO2Ss
- Faulty front heater O2 sensor
- O2 sensors harness is open or shorted
- O2 sensors poor electrical connection

you can buy an inexpensive code scanner at any pepboys or autozone and most parts stores scan your computer then go from there bank 1 is the side of engine where the number 1 spark plug is located they usually go anywhere from 80-120 thousand miles

replace the oxygen sensors. All of them, save the future headache.

1391 is a timing code cam or crank sensor
0134 bank 1 sensor 1 usually left front but double check
1684 doesn't match anything i know

If it is a 3.5 it is located on the front of the engine on the drivers side under the plenum.

There is only 4 sensors on a 2000 dodge intrepid and the bank 2 sensor 2 is the sensor located on the right (passenger) side and the one located after the catalytic converter (the one close to the firewall).

did you check for spark at the plugs. becuase oxygen sensor wont prevent the car from starting. let me know about the spark.

before you spend that kind of money you should plug it in and scan for trouble codes could be 1 0f 20 things???

I don't have a dodge ram but the codes for the dodge vehicles where pretty much the same. For my intrepid the codes read for the following numbers

12 - Problem with battery connection (This usually happens if you disconnect the battery)
21 - Problem with the oxygen sensor circuit
52 - Oxygen Sensor signal input indicates rich mixture during engine operation.

It sounds like you may need to change an oxygen sensor. Hope this helps.

Code 12 is: Direct battery input to PCM was disconnected within the last 50 key-on cycles.

Code 21 is: Neither rich nor lean condition detected from the oxygen sensor input or oxygen sensor input voltage maintained above the normal operating range.