Where would this o2 sensor be located and why would it keep going out in my 04 dodge ram 1500 I'm assuming it's the same one that has been going out in it and it's the one by the catalytic converter. Ive had it swapped before and i got it to pass smog but about a month after it threw the code again and of course i havr to smog it this year so any help would be awesome. Thanks and happy new year.

 

Passenger side, after the cat.

 

before you buy a new o2 sensor and still have the same issue, because that code doesn't automatically mean "replace downstream o2 sensor"
1 if relay for o2 heaters is tied to ASD relay (no clue with 2004), then you don't have to worry about because you'd also get no power to the injectors if it was bad if you have a separate o2 heater relay then check since you don't have to get greasy or crawl under your truck
2 test your o2 sensor connector for broken/frayed wires
3 probe your O2 connector. two are sensor and heater grounds, 1 is sensor output (you can test continuity from the terminal to PCM), 1 is +12v from the engine bay fuse box relay, for the sensor heater. OFC you won't see +12v with key off
4 after verifying good connection, take a good look at the metal terminals hiding in the connector. if they are all rounded and stretched, not getting a good electrical connection with sensor pins. You can fit a needle between metal terminal and plastic connector and gently bend the terminal back into shape.
you may have issue with sensor ground or sensor output terminal/wire before you jump the gun and buy an o2 sensor


good luck

 

I had a similar issue with my 04 1500, same position o2. Started with a inconsistent p0157, then a very repeatable p0058.. I swapped o2 bank positions, problem didn't follow. Visually and electrically checked the wiring, no problem. Concluded it must be the ecu. Replaced it with a used ebay ecu, had it programmed by the dealer, and no more issues. Pretty sure I had a couple threads on this forum when I was trying to figure out what was going on.