Dealer said $5k new trans, but scan says Generator Temp Sensor high?

Yeah, so my buddy bought an '07 from an unfortunate who has the dealer do all of his service, with their latest gambit being to try and sell him a used 120k mile tranny for 5-grand. The car has 270k-ish miles, so he felt he'd gotten his money's worth and let it go cheap cheap. Dr. Prius shows a bad mid cell in the hybrid battery, and the 2-year old12-volt was a little undercharged (barely 12v. as I recall). Lights a-plenty were lit: Red Triangle, ABS, VSC, TPMS & brakes, so we dollied her home, but here's the thing. The car runs great, getting 49 mpg after some filter changes and topping off the 12 volt. Don't have TechStream, but I do have a pretty nice Chinese tablet (Launch, but I see the same unit rebranded by many) that's been good to us.Scan also showed a beat module (#9 I think) but it also threw a code we haven't dealt with before: Generator Temperature Sensor Circuit High POA39? Any ideas or suggestions?

A/C is ice cold, brakes are solid, hybrid cooling fan and duct were cleaned but were already running fine, cabin filter was cruddy, as was the PCV valve, but transmission was absolutely fine. Car starts and runs great. Coolant pump circulation looks strong, but also getting C1310 (HV System Malfunction) and B1421 (Solar Sensor Circuit - Passenger side) faults.

Generally we've found that most of these codes resolve once the two batteries are up to snuff, but this Generator Temperature Sensor fault is a new one to us, so any help would be much appreciated. He got me into these Gen 2 Prii, and right now I think our two families have ten or eleven of them between us, so a factory repair manual and hybrid charger are on the way, but meanwhile we're stuck.

Also wondering, what are the forum rules on calling these service writer scoundrels out by name?

 

Thank you all for your very helpful & considered assistance. My default is generally that most codes are somehow triggered by a primary issue w/ one or both of the battery systems, but until my new gear arrives I'm still not out of the woods w/ regard to said batteries, so until then I'm still somewhat tilting at windmills. Meanwhile, I'll certainly be following up on all of the helpful proffered links and information.

I'd also like to apologize for not having found the cited Prius Chat references before posting this. I'll be reading them straight away, but I did attempt several searches beforehand with no joy, so I'm guessing I need to refine my searches. Being one who is constantly annoyed by lazy arses who post w/o first searching, I feel compelled to at least offer this rather weak mea culpa.

Beyond that, I have to say that this forum in particular has been a truly wonderful resource, and I very much appreciate the time & efforts of the folks who contribute here. You all represent a kind of virtual therapy for my expanding Prius habit (as Wife Number Last refers to it). Nice to know we have a "support group".

Lastly, agreed, TechStream is now top of my list of essentials, so thanks for that reinforcement as well.

Now I just need to find a little monkey to train to install window tint to survive our pretty brutal summer sun. Getting a hip replaced in a couple of weeks, so not quite as nimble as my 18 year old head thinks my 63 year old body is. lol