Prius C 2012

Probably a weak 12v battery.

This is a ~$220 part at most Toyota dealers. Very difficult to get the right one anywhere else. Toyota will install it for you for a bit more if you want, but it's an easy job and you might do it yourself or have a cheaper neighborhood mechanic do it.

 

I agree with Leadfoot. Most likely a failing 12v battery. If it's the original, at 8-9 years and 176k miles, you definitley got your money's worth out of it. Dealer can check the condition for you. I wouldn't wait too long to have it looked at. It may not get you through a NH winter.

 

Exact same thing happened to me I recognize that symptom

 

If you are they do it yourself kind of person in Automotive Incline gifted.

I would skip the dealer it will charge you $150 + diagnosis fee Spend another $220 plus for the battery plus the labor to install the battery then the labor to clear the codes and the labor to test the system you will come out of the dealer with a $600 battery.
That’s what happened to my ex-wife in her Prius when she went to the dealer here in San Francisco.

 

Yeah, a lot of dealers will nickel and dime you to death. Guess I got lucky. Mine waived the diagnostic fee as long as I bought the battery. Not much you can do about the battery cost. I paid $212.00, but it's pretty much the same most places. Installation was $65.00. WIth having to dig under the rear seat, and also maintain the trickle charge to not lose the infotainment center settings, I was willing to pay that. But DIY wouldn't be that difficult if you have the tools.

 

Me too.
But yours is about the age where the door lock actuators are likely to fail too.
Low battery voltage might make them act up a bit before a total failure.

 

Similar symptoms here: 160k, weak door lock sounds, also dim console lights and slowing "wakeup" response to the start button. Symptoms lasted for a few days, then had to press start button a couple times, and increasingly got worse until the car would not start at all. I noticed the EVO switch setting memory got reset. Posts here were very helpful identifying the most likely problem: the 12v "half size" battery under the rear right passenger seat.

In June 2022 dealers were struggling with supply chain issues and quoting "2 weeks" to get a genuine replacement - yeah, no, I need it working tomorrow. Aftermarket FTW, oh Riley had one for $220. One authorized Toyota dealer offered to sell me a battery "today" for $370?! Scam artists.

Was able to replace the battery myself - careful to remove the negative/ground connection first (and reattach it last) so wrenching on the positive post couldn't short to the car chassis. Also careful to reattach safety lugs and post covers. Car started right up. That battery died 10 years plus 2 weeks after I bought the car ... had a 10 year warranty ... yeah, they've got the sulfation and loss of electrolyte timing down pat.