2010 Prius - P Brake Malfunction & Hybrid System Overheat Messages

Hi All,

I'm sure I know the solution to the problem, but I just want to throw this out there just in case there is something else.

So I have a 2010 Prius II with 27,218 miles. I know, shocking with the extremely low mileage. Anyway, I'm in Orange County, California. On Friday, January 7, 2022, it was a cold morning and when I went to unlock my car via the key fob, it was unresponsive/very weak. I immediately thought it was the 12V battery. I was able to get in but the Push Start basically was showing RED instead of the normal GREEN, as well as taking a while to light up. I immediately got the CHECK ENGINE light displaying. Next, got the error message of P Brake Malfunction, in which the P button was blinking on and off green. Clearly, I could not get that button to engage. I was parked on a flat, leveled surface. Furthermore, there was a delay each time I pressed the PUSH START button, in order to turn off the car/display.

The only other time I have encountered the P Brake Malfunction message was 7 years ago when my battery died, so when I show that message again, I had a feeling.

Now, I also received the HYBRID SYSTEM OVERHEAT message shortly thereafter, which didn't make any sense to me as the car didn't have a chance to get warm, as well as the coolant levels are between the MAX-MIN.

I clearly was unable to drive my car to run errands that day, so I used a different car for my errands. When I came back after a few hours, the P Brake Malfunction was still displayed but I was finally able to get the car to start. I quickly did a lap around the block.

The rest of the day was making phone calls in terms of getting price quotes for a new 12V battery. I know that if there is not another power source when switching out the 12V battery, the radio presets gets erased. I also don't know if that would also erase any error codes that might show up. I typically get an oil change every year, especially since of the low annual miles, which is next month, but I don't know if those error codes would still show up.

I know too often of taking the car in for service and explaining the error messages, but unfortunately they are not able to replicate.

Anyway, I'm pretty sure that it is the 12V battery that is the cause and something that definitely will be replaced shortly. Just wanted to see if anyone else has experienced something like this and if the 12V battery is the reason. Interestly, I had driven/started my car just fine a week prior to that issue. Oddly, I have driven and started my car successfully each time since that Friday and no more error messages.

Thanks for listening!!