The first 24 months my pickup had 10 NOX sensors fail. They were all covered under GM warranty. I discovered that ALL the times the NOX sensors failed was when I was using cruise control. The last 60 months I haven’t used the cruise control at all and haven’t had ANY NOX sensors fail! The mechanics at GM can’t believe this, but I can’t argue with the results!

There'* no reason for that to do anything.

I speculate that this is because the engine is held at one speed, and doesn't rev up or down to either blow some soot out or reduce stress or heat or etc. Maybe the particular speed that you generally use the cruise control at puts the engine at some perfect storm of circumstances where some part gets upset about it'* conditions. If you are using the cruise control in rolling hills or mountains where it shifts down a lot then my hair-brained theory is blown out of the water.

I bet you could get the same result by using the cruise control like before, then occasionally blipping it down a gear or two every 20-30 minutes for 30 seconds each time. Again, if it already shifts down due to hills etc. then my theory is blown out of the water.

It would be an interesting experiment though.

The only other thing I can think of is that maybe GM has emissions regen mapping running differently with cruise control active because it can do it differently and/or better in known-ish conditions . . . ? I'm really stretching on that one but it wouldn't surprise me if someone there came up with something like that.

Other than those two explanations, I guess it could be possible that you got an improved design during the last replacement . . . ? Seen that before as well. If you have the paperwork for the other replacements, it would be neat to see what the part numbers were each time they installed parts, especially the last one.

While driving on interstate highway there is only 1 overpass over the railroad tracks that the engine would have to shift down. The rest of the 80 mile drive is perfectly flat, and the cruise was set @79mph for both directions. RPM is around 1800 at this speed.

Okay then my hair-brained theory isn't dead yet, but still really difficult to test.

Now that it'* gone five years without issue, maybe start using cruise control again and see if the problem crops up within 90 days (based on your original 10 units in two years rotation). Maybe the current sensor is an improved version, or was installed properly for the first time or something.