Have had a MIL/CEL indicator pop up intermittently over the past few months. DTC code indicates the NOx Sensor #2 is faulty. Before I could get to replacing it, the indicator went off. It has come back on, then gone away a few times since then. I logged the real-time data from it a couple of times while driving, both during the malfunction mode, and in normal mode, and can't really tell much difference, if any. I don't even know what the normal range is, it fluctuates widely, depending on throttle setting, etc. (But so does the NOx #1 output).
Anyway, Rock Auto has an OEM GM part for about half of what the parts stores are priced. I was just about to buy it, but noticed on the specs it says "Programming Required - Yes".
Is this true? And if yes, is it something only a Dealer can do, or would an independent Diesel shop be able to program it?

Thanks in advance for any info. or advice.

Jim, the Rock Automotive is most likely a copy, not OE.

Other than clearing the codes, I've never had to program a nox sensor when I replaced them. Just had to use a scan tool to verify it was doing what it was supposed to be doing after replacement.

OE parts from Rock Auto are usually OE, as are many of the other replacement parts. They do offer the cheap ones and off brands but stay away from those on emissions stuff. When I hit the deer in my Subaru, Subaru wanted $1100 for the nose on my car, a one piece molded plastic cap. Rock Auto had it marked as an off brand for $99. I figured it was worth it to see if it fit....when the box and other parts I ordered from them arrived, ALL OF THEM were factory Subaru parts in the OE boxes.....I love Rock Auto, get all my spark plugs there too

Update - Just to follow-up and close the loop on this one...

Local O'Reilly store was priced at $347 for an aftermarket brand. Ordered the Downstream NOx Sensor from Rock for $1 more than Half-Price, $174. I went with standard shipping, it took 5 days to arrive. It was the same GM part, although made in Czech Republic, (original was made in Germany). Easy installation, and interestingly, I had my scan tool connected on startup, and it popped open a window and asked me to Confirm (or Verify) NOx Sensor 2. I don't know if the PCM somehow detected that it had been changed, but I hit Ok, and the initial reading was very low and did not vary at all. After a couple of minutes the readings began updating and looked what I would call normal.
Cleared the fault code, and have driven it over 800 miles since, with no issues.