ok, here is what I found in my Factory Service Manuals...
P0031 - o2 sensor 1/1 heater circuit low
P0051 - o2 sensor 2/1 heater circuit low
P0136 - o2 sensor 1/2 heater relay circuit open or shorted
P0152 - o2 sensor 2/1 shorted to voltage
P0175 - o2 sensor 2/1 fuel system rich
P0460 - fuel level unit, no change over miles
my opinion is such...
P0031 & P0051 are related, and I had a similar problem recently... there is a 5-volt regulated power supply in the PCM that supplies all the sensors a basic 5-volts to operate. my front sensors were throwing this code just as yours are... I thought there was something wrong with the front sensors... but after changing them, the code remained. after looking at the wiring schematics, I discovered a flaw in Chrysler's design... the 5-volt power tap used by the o2 sensor heaters goes to the rear sensors first and then to the front... this is important because the sensors heaters are electric resistance heaters... for if your resistance is too high in the rear it will supply too much voltage to the front and if resistance is not enough, then there will be a shortage of voltage up front... because electricity travels in the path of least resistance... well, after pulling the rears, I discovered that they were the wrong sensors for my year... after 2002, Chrysler vehicles have different front and rear sensors... they are not universal after 2002... so I caution you to check your rear sensors...
P0136 & P0152 you found with the blown fuse... don't know what happened there, but may be related to your adjustments
P0175 is a no brainer
P0460 is very interesting... it took me forever to find it... Chrysler PCMs store MPG in the computer for use of overhead readouts or the use of a DRBIII (Chrysler's proprietary ODB reader)... the reason it's so interesting is that usually only MAF-based cars have MPG in the computer... MAF-based systems can calc MPG on the fly... Chrysler doesn't use any MAF systems, they are MAP-based engines (usually no MPG being calc)... it's what allowed them to get the EPA to allow them to build cars without EGR valves, of which they have not had since 2002. they showed the EPA that their engines had less emissions without and they were given special permission to remove them... it was a very cool thing... anyway, sorry to get off topic... so the computer actually monitors the level in the tank as part of the mileage... I'm going to check into this further... it's very interesting... basically, it looks for a certain amount of change in the tank after so many miles... I don't know what those variables are, but I will find them and post the info... so if you took a Chrysler vehicle and got it to 100% hydrogen, or even just beyond what the computer expects, then it will throw this code... so much for having hho and no codes...
I will keep you posted on any more I find...