2001 Dodge Ram P0138 code

Yes, the code that reappears is the same P0138 code that was showing up before. If you have any ideas, please let me know. I could use a digital voltmeter and follow the instructions to monitor the voltages to see if the sensor is working properly. It's not a hard job but it isn't the easiest either but if I have to, I might try that. As mentioned before, I have replaced the sensor already. Is there a chance the problem could be with a version of PCM software. I have to see if I can find all my paperwork but a while back, I had an upgrade done to the PCM at a dealership. I had the P0138 code but didn't rush on it since it was just an oxygen sensor and not something like faulty brakes (sensor was not a real safety hazard). I want to find out if the timing is about the same (when the code showed up and when I had the upgrade). Let me know what you think. Thanks again.

I could check the wiring but that's not an easy job either but since I'm going to possibly be going up there (you can't see anything up there), I'll do the digital multimeter thing to check to make sure I didn't get a bad sensor or something stupid like that. I'll check into it and get back to you no matter what I find. I live in Winnipeg, Manitoba, Canada (known as the Great White North but not that bad) and the problem seems to have materialized after I was shuttling medical staff during one heck of a storm we had. I took a quick look the first time to make sure no loose wires were hanging around but the code comes and goes so it may be a bad connection that makes and breaks now and then so I might have to move some assemblies out of the way to get a good look because the touchy feely method might not be good enough. I'll get back to you wheteher I find or don't find anything. Later.