U0100 and 15A fuse at #30 EFI blown

2009 Prius, 158K, returned from a long road trip, oil change last month, air filter changed, PCV changed because I noted oil burned during the road trip 10K like 3 qt. it is hot 90F today, but the car has been to death valley with 117F a month ago and had no problem.
Driving as normally, suddenly triangle ! showed up, pulled to a parking lot and found that I got U0100 and someone mentioned 15A fuse at #30, so I checked and sure enough it was blown. He mentioned O2 wire rubbed again the body, but I don't know how to look for it - I know of the front next to the engine and rear next to the catalysis converter.
Fuse replaced, code cleared and I drove the car for another mile before the light came up again. I was able to continue driving back to the garage. same code, same fuse blew. This time I see there are code P3000 with the hybrid battery ECU (which I never looked before - I just read the first ECU that pops up with code).
I do have a cat shield, a stainless steel cage installed 3 months ago before the road trip (10K driven no problem, but I have been "scratching" the bottom of the car with it when the car was loaded up, looked ok from the side.
I heard some rattle on the steering column for a long while - it was not part of the recalled.
the highway has been doing lots of construction, I heard some noise only while driving on a scraped road surface.
I want to know how to find out what's control by this fuse so I can start looking for possible problems.

 

I have been reading many posts and some said it is the O2 rear sensor (google EFI fuse problem prius). There is also a post that mentioned don't bother with o2 sensor, but check the MAF, VSV and o2 front sensor (Air fuel ration sensor). That are 2 different directions - what am I missing - it is the the first 15A fuse on the far right of the fuse box that is blown, twice for me, so it is not fuse being old but something sounds shorted.

 

It turned out my problem was that the gen 2 cat shield opening on the side for the o2 wire is rubbing the wire and caused a short. The quick and dirty solution was to cut the shield (stainless steel) a bit more so there are more room for the wire to bounce around on rough road and not cutting the protective covering. For now, I electrical tape the area where the protective covering was cut (hoping that will withhold the heat from the cat) Will inspect periodically to ensure. Lucky with all the posts on u0100, efi fuse blown that lead to this finding (would even know where to look if not going through all the posts). So many people having o2 sensor wire shorts (caused by exposed environment, not cat shield), this is definitely a weak spot of prius, there should be no exposed wire that just hang out underneath the car. I can't find the delete the thread, but hope this will help someone else.

 

There is not much slack - the edge of the opening of v2 cat shield is just too close to the wire. I cut 2 inches to ensure it won't even come close. I am aware of the wire under the carpet in front of the passenger seat - that's where I disconnected the connector to test the short of the fuse. It did not cut the wire, but cut the protective covering, but the touching causes the short. I never expected to install the cat shield in May, 2023 and ended up cause my car to get tow on a very hot day, I consider that a design flaw and waste time and unnecessary stress.