need more details with my vsc and ! light on

2004 prius
Runs great after I did all the maintenance. Plugs, atf, coolant flow control sensor, oil, filter, cleaned tb, new coolant, inverter pump is fine.

Vsc and ! And red triangle are on
Only code is vsc 51 aka C1310

Any advise would help. I'm a retired master mechanic and would prefer to figure out the source of my problem myself.

More info is that the vehicle was in a front end collision. What I notice is during the first 5 minutes of driving, the brake regen doesn't work when I let off the gas pedal. The display screen still shows energy going towards the wheels instead of the green regen going back into the battery. It only does this for a few minutes. It will work if i step on the brake pedal though. I think it has to do with the vsc being pulled back to limp mode or something to that nature. I've tried doing the 8 pump brake technique with no avail in order to reset the code but it didn't work.

Also the driver's side fan kicks on all the time. Usually at start up and stays on all the time.

 

I've been doing my research for a week before I was forced to post the thread. Can't find anything with more in depth detail concerning the vsc 51 c1310

 

It's the driver's side radiator fan
I'm working on a friends prius who is not that mechanically inclined. I did all the maintenance before I had to leave Washington. Cars drives great besides the vsc light. Won't be able to get back to it for another 2 weeks so I'll keep you informed.