DEF Pump RPM's too high for the pressure

My truck is throwing SPN 4374 FMI 0 /pump RPM's higher than normal for the given pressure. I replaced it nearly 30mo ago. I noticed that during these codes and when I was derated 25% power, at any given time the DEF level was not reducing. After nearly 1000 miles of this and waiting 5h to load at a shipper, when I finally departed the DEF began flowing again and the code and derate cleared. All the next day it flowed dropping the level from 100% to 88%. Then the code came back illuminating both MIL, CIL and the 25% derate. About 50 miles in the truck derated to 55mph. Signifying that I had been experiencing SPN 5246 FMI 0 which had now gone to SPN 5246 FMI 15, the dreaded EPA codes. I was worried and should be but wasn't sure convinced of the inevitable when I crossed the border as I would be forced to stop and shut down the engine. In the past and under different circumstances I'd seen it derate to 5moh just by going under 5mph and without a key cycle. When I pulled into Customs I did have to stop at the line up and it did not light up the SIL . And I keyed off at the booth. Started fine but as soon as I moved the SPN 5246 FMI 16 threw, derated me to 5mph 85 miles from home. The One Box is new, as are DPF filters. And the harnesses. I'm hoping that a new DEF pump filter will resolve this as all the lines and even the doser are all newer components. I've spent over $30,000 on this EPA implemented teenage high school students pollution control emissions garbage over the last few years passing and all I've learned is that no one really has any insight into these systems and that's because it's not a naturally evolving technology like the internal diesel combustion engine, but some pencil pusher's adaptation. And I say this over the neglect of legal implementation considered in the introduction of these technologies that have the ability in certain circumstances to force a driver to be stranded when the engine can still get along down the road because it's absolutely fine.
During last year's numerous out of control wildfires in Canada, where I've driving within 100 yards of visible flames accelerating (the flames not the truck) what could happen in remote Canadian bush country with infrequent traffic in such circumstances.

 

Well it's the magnitude that Caterpillar deserted the industry of On Highway Diesel Engines that stuns me. I had a Bridge Engine in a 2004 Peterbilt that didn't meet emissions regs and had a sticker on it that said CAT paid a penalty to market it. It ran very hot. Fan didn't come on until 225°. I believe and have heard rumors that when the EPA was dictating to CAT engineers this was speaking out of control. And you have to look at how CAT stood behind their engines with warranty obligations. And then take a look at Cummins' Progressive Warranty for a good laugh . Don't forget to read between the lines.