Multiple Diagnostic codes P0505 P1121 P0205 P0511

I recently purchased a 2005 Prius, 160K miles. This is my first hybrid car. Also my first experience with a Check Engine light on any car.

It runs basically well, the ICE is perhaps a little loud and choppy, but given its age i didn't think much of this. Other than the lights and codes i have no particular indication of any problems.

On the way home from buying this car (!) i got a check engine light. I kept driving and after ~40 miles including 20 miles on the freeway, I also got the High Voltage System warning light. Not happy about this but I'll spare you. I didn't drive it much for a couple days, and I started getting my act together, and used Car Scanner on my iPhone along with a Bluetooth 4.0 LE adapter to retrieve the following codes:
P0505 P1121 P0205 P0511

This car has I contacted the girl who sold it to me, as nicely as possible, and she told me (now, not earlier) that this has been happening for a long time. Well, it sounds like the check engine light has been coming and going for a long time, and the high voltage light more recently. Toyota dealership couldn't figure out the check engine light but they replaced a lot of stuff in the process, she says - she reported having had the O2 sensor replaced as well as all 4 water pumps. She blamed it on a bunch of BS about the prius being too sensitive. Some crap that a "mechanic" who couldn't figure it out probably told her (whether or not at a dealership).

I read that a combination of these lights (CEL+HVS lights on the dash) can be caused by a failing Inverter Water Pump. But this was supposedly replaced after the problem started. Reading more, I stumbled upon another proposed cause, a failing Water Valve Assembly Valve With Bracket. Sounds reasonable.. I can do this, hopefully myself, but I don't want to throw money away replacing random stuff here.

The other codes seem to point vaguely to an "injector circuit malfunction" on Cylinder 5. Pretty sure this car doesn't have a cylinder 5. I do see some indication about cleaning the throttle body. This sounds like a reasonable thing to do, not too hard or expensive, i guess i can go ahead and do that this weekend.

Can anyone give me some insight on this?

Thanks so much for your helpful replies.

 

Ok. I am the OP. I fixed this.

All the CEL codes were fixed by:
Replaced Coolant control sensor thing mentioned above,
Replaced air filter
Cleaned MAF and air intake

The red triangle was because of the headlight adjustment sensor in the back, had to replace that plus the wires leading into it wow. Additionally the HID headlights were all F’d - I’ve heard this costs $$$ or $$$$ but I fixed that for $55 by switching to LED and cleaning the lenses. Took all day just to do this tho!

 

Yep. The lights are fine. The deal is that if you have halogen lights then you can buy a better brand, opt7, I think the type is H4. Anyway my car came with HID headlights and these are an adequate not awesome replacement for that. I removed the ballasts and soldered the new connectors onto the wires that used to go to the ballasts. Not too complicated but it took me all day one day in the summer.


iPhone ?