With ~84K on my 2 year old Silverado, I'm seeing yet another series of error conditions. The latest, being the U029E code which, per a web search, is a "Lost Communication With NOX Sensor B". The CE lamp also activates on the instr panel. Further, I am also getting intermittent displays of a DEF level failure that comes and goes (corresponding IP indicator sets & resets), which also displays 2 different messages related to "miles left, with the speed limited to 65 mph".

Via my Edge monitor, I see that my DEF tank pressure is at 0 psi until I drive a mile or two, after-which my tank pressure exceeds 70 psi. Clearing the error code immediately resets my CE indicator. Given that I've recently encountered intermittent P20EE codes (SCR NOx Catalyst Efficiency Below Threshold Bank 1), my hunch is that these faults are inter-related.

Could it be possible that the lack of (or low) pressure on the DEF tank is resulting in weak/NO fluid from the DEF tank, thus, impacting the catalyst efficiency? With "no communication" coming from NOX Sensor B, is this sensor clogging with soot (or, defective) and, would the lack of tank pressure also suggest a soot buildup at/near the DPF?

I'm beginning to have a strong dislike of all this emissions control bull S#!T. Per my OnStar reports, I have NO recalls for my VIN with the L5P Dmax. And I question if any repairs to this system would be covered under the remaining warranty on this vehicle.

Thoughts, anyone?
And Thanks again!