2005 - Brought Used Vehicle with Several Problems

The radiator flush was not a priority, there's no immediate issue with P1150, as this doesn't affect the car while it's running. Now with P1121 present, you may have to drain that radiator again to change the valve out. I guess if you have the right clamps, you can avoid the radiator flush by clamping off the hose while replacing the valve for P1121. Did your mechanic use the proper pink Toyota coolant?

The main issue with your car is still the HV battery, the other issues are not as important or as expensive. P1121 will not cause your car to break down, but the HV battery failure will cause it to break down.

 

1. How well does the cabin heater work? Do you hear any air bubbling in the system?
2. I am concerned that if the engine is in fact overheating, that may be due to air in the cylinder head.
3. If you believe the engine coolant system does not have any air in it and P1121 is logged then it is time to change the engine coolant valve.

 

Did Toyota tell you that you need a new HV battery? If not you need to get the proper Toyota tech stream obd2 reader. If you do need a new battery used batteries seem to be the best alternative if you're on budget. The big question that pops into my mind is "did you get a good deal on your car?" If you did than it's all good, if not you might want to consider small claims court or some other avenue. We have a local wrecker here that will sell used high mileage batteries for $300, low mileage for around a grand. It's not that difficult of a diy job from what I've seen...

 

...sorry about that too bad, might have been better if the orig owner had made this request.

 

1. The question #1 in my post #22 above needs to be answered.
2. Now that you've driven the car a few times since the coolant was worked on, check the engine coolant level (at the radiator itself, do not rely upon looking at the overflow container.)
3. I suggest that you do not drive the car extensively while this overheating problem persists.

 

1. The engine coolant loop most likely has substantial air in it if the cabin heater is not working now.
2. Yes, you are looking for the silver twist cap and need to remove the large black plastic cover over the radiator for access to the radiator cap. See how much air is in the radiator now.

DTC P1116 is related to P1121 and means that the coolant heat recovery system temp sensor at the CHRS canister is not registering the correct temperature value changes as the system operates. This is probably related to trapped air in the system.

I have previously posted on how to change the engine coolant and purge the coolant system. See my posts #22 and #42 here:
Changing engine coolant | Page 2 | PriusChat

You may want to follow my instructions about how to do this since it seems that your mechanic did not do a complete job. Make sure that the pink Toyota Super Long Life Coolant was used. If this coolant was not used, that is more evidence the mechanic took shortcuts.

 

This might be a record amount for repair quote on a prius. I can't even begin to imagine what can cost that much money on a car that still runs, but has issues.

 

Sounds like the repair estimate included, "Buy new car from our Sales Department".

Seriously, though, I'd love to see the printout of the estimate.
(personal info edited out, of course)