I have been trying to fix this problem for awhile now. 2004 Ram 2500 4x4 with a 5.7 Hemi. The Engine light is always on. Before I did anything I fixed the exhaust leak which had the manifold bolts that were broken. That did not help, the light stayed on. I then had it scanned, I don't have a scanner. Ok it said O2 left bank / upstream. I replace both upstream sensors the light goes out for about ten minutes then back on. It is on for good again. I had replaced all sensors about 5 years ago also. What to do?
Bob

Without the exact code any answer would only be a guess.

I had it scanned a few times, every time it said O2 sensor.
I realize that it would by a guess but before I pay to have scanned again I am sure it will say O2 Sensor, then what.
Thanks Bob

Look for a burned wire or corroded connector on the O2 sensor wires. My son had that issue and discovered a place on the wire to the sensor that must had been against the exhaust at some point. He replaced the wires and all has been well for a few years. A shorted out sensor wire could have damaged that port on the computer.

Look for a messed up injector or vacuumed leak, or an exhaust leak on the bank that has the fault code.

The computer tells you what is not getting it the reading it wants to see, that doesn't mean that sensor is bad, it means the computer is not seeing the numbers it wants on that circuit. The problem could be something mechanically wrong with the side that gives the code.

az scans for free. most of the time when people are told what the code is, they only hear a few words that is said to them. like bank 1 sensor 1 lean. does that mean that the o2 is bad? maybe/maybe not. the code gives a general area of concern or a symptom. it requires a test to determine what is actually wrong with that system. billions of dollars are spent each year on parts that people throw at a cel because they don't want to pay for diagnosis. most of the time the part has little/nothing to do with the actual cause of the cel. pay for diagnosis performed by a qualified ase/respected mechanic.

And get the number. The shorthand version The counter guy gives is worthless.

You need to start with the actual code number. I can think of at least a dozen oxygen sensor related numbers that have different diagnostic processes.

[quote=trw1982]az scans for free. most of the time when people are told what the code is, they only hear a few words that is said to them. like bank 1 sensor 1 lean. does that mean that the o2 is bad? maybe/maybe not. the code gives a general area of concern or a symptom. it requires a test to determine what is actually wrong with that system. billions of dollars are spent each year on parts that people throw at a cel because they don't want to pay for diagnosis. most of the time the part has little/nothing to do with the actual cause of the cel. pay for diagnosis performed by a qualified ase/respected mechanic. [/quote

I received the info from a Dodge tech. So now that I changed the sensors I will am aware that I need to look into more of a problem.
Thanks to all
I was just trying to think outside the box with all of you help.
Bob

Our Yukon has had an 02 sensor code for years just one side. New sensor, wires all OK. The last garage that checked it thought there might be something wrong with that cat causing it even tho there were no signs of that. Now that they scrapped emission testing here and prices of the summit type exhaust systems have gone up thanks to the pandemic it's less of a priority now.

This^^^. It could be rich, lean, slow to change, heater circuit, etc. The code didn't just say O2 sensor, it said something about that sensor as well.

I checked all the connections and wires, they look good. The next thing to do is go back to my friend at the Chrysler / Dodge / Jeep dealer and check it out again on the scanner to find out more info.
Thanks Bob

I'm surprised it was not corroded connections at sensor as poorboy suggested. Hope you solve this soon.

Any autozone will scan it for free to get the code.

THEN diagnose as needed per the actual code