I'm sort of familiar with things common to fail on the full-size Gen 3 Prius, but not with the c. What should I be looking out for? I do plan to run TechStream report on it, check the battery cells, etc.
The Prius "c" is incredibly reliable and im not sure you will find "common" problems. I actually cannot think of any problems to post for you. As long as regular maintenance is done, should give trouble free service. The only concern for buying used is the HV battery, which has an 8 year 100k mile warranty. All bets are off after that warranty expires. You can also read this thread if you have the time.... Prius C who-has-highest-mileage-on-odometer
"Common" in that issues may not be frequent but having the highest frequency of those that may occur. For example, I assume the wheel bearings are the same fragile ones used in the full-size to be more efficient than possibly long-lasting. I have had to replace one of those after only 70k miles. I'm just wanting to know what may be most likely to go wrong on this model even though that may not happen until 200k. That thread you linked, for example, noted that automatic door locks are an issue.
The climate control "OFF" button sometimes sticks, It will not turn on making you think something is broken. But a tap or few on it will release it so you can use it normally.
Automatic door locks have already been mentioned. But the HV Battery life (from what I've seen around here) seems to be a bit shorter than the regular Prius. 5-6 years seems to be what is generally seen. Possibly due to it being a smaller battery than the regular Prius is the general assumption as to why. I don't recall ever hearing about anyone replacing wheel bearings though. Other than that, you don't really see much else reported. The "C" has a very good reliability rating.
People aren't replacing wheel bearings because the failure mode is rarely anything beyond increased noise, and the onset is extremely gradual. But the same problem has been affecting the majority of Asian cars of many makes for a decade+. They literally don't make them like they used to. My last two Outbacks and a pair of Altimas in the extended family all saw bearings go loud at 60-75k. The battery isn't as robust because it's a bit smaller, so any individual cell weakness has an amplified effect vs. the bigger packs in the liftback, hybrid camry etc. It's also cheaper because it's smaller. They are very sensitive to battery temperature. A clogged battery cooling fan can stop one in its tracks. The designers anticipated that the driver would use a fair amount of air conditioning which coincidentally works to cool the battery, since it breathes cabin air. If you're into stats, it's the second most reliable car in America, behind the Lexus GX.
I learned that was another common issue though an easily fixed one. This one had minimal lint buildup.
Well there is one......that seems common to a lot of models: The electric door lock actuators (solenoids). I had one fixed under warranty, just shy of 2 years, and the second went around 3 years. My family has had 4 of them now.
Found another (though apparently other Prii have similar issue) - roof molding likes to come off. Didn't lose mine but have taken them off for now.
Not sure I know which molding you mean. I might not have it anyway, they changed a lot of the detail trim for 2017+ models.
There is a channel on each side of the roof......that runs front to back......and is intended, I think, to attach something like a luggage rack. With the older models, the decorative "trim" that covers the channels was soft rubber that tended to stretch and come loose. I just looked at mine and it's still there, but appears to be a harder plastic material now that should stand up better. No really good reason not to just leave it off if/when it comes loose.
Yes, many cars have some kind of plastic strip in those channels, and I found complaints from pretty much all non-current Prius Gens about them coming loose in wind or car wash. I had noticed the looseness on mine and then we had a very windy day yesterday and one actually started flapping in the middle as I was in a crosswind right before my work. I removed them before driving back home.
Yeah, mine came loose as well, but it's not just a Toyota thing. Happens on the Honda's as well according to my son. (He's a Master Honda Tech) Mine were replaced, but once again when going thru the car was they came loose. So I put some 3M adhesive in the channel and reattached them. I've never had a problem since.
To increase the commonality on some previously mentioned items, these have also been issues on my 2012: 1. Trim in roof channels coming loose (only in the car wash for me) 2. Climate control OFF button sticking Not mentioned yet here, and more an engineering or assembly defect than a failure. are the noises, vibrations, rattles and buzzing, etc. that come from the dashboard, usually the passenger side. Many, including myself, have solved this with rubber/cardboard shims in various locations where sections join. I just hit 130,000 miles and haven't experienced any wheel bearing noise, or any other failures yet (he says crossing fingers ). Just had my hybrid battery tested. It shows 84.9% life remaining. Running on original brake pads, which you have no doubt experienced similar with your other Prius. The previously mentioned "incredibly reliable" comment works for me as well.