Master Warning Light, P1121, and P1123

Hey there all,

I bought my 2005 Prius last year, its my first car, and I've already fallen in love with it. A little while after purchasing the check engine light came on, and the dealership (after taking $200 for the diagnostic fee!) told me it was giving them the P1121 error, and that the coolant control valve had to be replaced. I rode around on it in the past months since at first I didn't have the money for any kind of repairs, and now that I do, work has a much too firm grasp on me and I have 0 free time. It's at ~151k miles right now and I've driven it less than 2k miles in the time I've had it - my workplace is really nearby. Also, the battery was replaced upon purchase by the dealership because there was some sort of issue with it.

I was affected by the deep freeze the south experienced this past week. Everything was okay for the first few days, but on Thursday evening when I was coming home from work, I turned my car on as usual but then the master warning light, VSC, and (!) lights all came on at the same time and stayed on. I'm sure part of it was due to the cold; this morning the VSC and (!) lights turned off, but the master warning light is still on. Using a diagnostic tool from Autozone I was able to pull the codes P1121, but now also P1123 which wasn't there before.

Is it safe to drive on this, at least until I get the replacement part and I find someone who can install it for me? I don't really go above 35mph and my drive to/from work lasts maybe 3 minutes. Nothing really feels any different, the heating works for sure and breaking/accelerating/turning feels fine as normal. The light consistently says on when I turn the car on and when I drive though, no flashing or anything. I've seen some people recommending that I check on the coolant and oil too. Would those be necessary considering I use my car so infrequently? (And if I flush the coolant - is there anything in particular I need to do to make sure I'm disposing the fluid correctly? Where does it go when I flush it? I don't have a garage or any sort of space or tools to do something like that Reckon someone at Jiffylube could help me if I stroll up with my bottles in hand? lol)

Sorry this turned into a novel - I'm a bit long-winded and I wanted to be as detailed as I could!

 

Phew, I'm glad I don't have to rush it. Here I was thinking that after driving on a check engine light for so long, the master warning one came on because it finally had enough of my procrastinating

I'll definitely have to get the battery checked out then, hopefully on Tuesday if I can find someone willing to check it. It seems like everyone around here is too scared to even look at hybrid vehicles lol. I didn't know about battery maintainers though - are there any particular ones you would recommend?

The mileage is at 151,000 right now, got it at just shy of 149,000 last summer. I should ah, definitely check the oil levels though. Its something I completely forgot about! Nothing is showing up when I plug in my VIN on Toyota's site though, and now of course my internet is being slow and the free VIN checkers aren't working. I am seeing that I should get it checked every 6 months if I don't hit the 5,000 mile mark in that period though.

 

Just checked the 12V battery readings in vehicle signal check mode. With just having the power on I got 12.2V, turning the ignition on and leaving my foot off the break gave me 11.8V, but putting my foot on the break and fully turning the car on gave me 14.6V. Could that be the culprit, even though its mostly over 12V?

 

I see, thank you. Do you think I would be able to save it with a battery maintainer? Or would it have to be replaced at this point? I'm probably gonna trade it up for a newer Prius sometime within a year or two honestly; reckon it can last that long?