2015 Prius c, Check Hybrid system

Hi all, I drive my car every day, the last time being yesterday morning (around 36 hours ago). When I went to start it today, the gas engine came on for about a second or two then shuts down (it feels like it dies as it rattles around quite a bit as it stops). The display shows Check Hybrid system, stop car in a safe area or something like that. For a few weeks now, it has shown a message about upcoming maintenance needed, which admittedly I hadn't looked into as the car has been running fine. (I just googled and I read that this is the regular every 5k message, though I don't recall seeing it before, I guess I could just not remember). The car has about 67k miles.

I borrowed an OBDII scanner from my dad and it's returning codes P0121 and P0222.

I have read on here that low 12v battery voltage can cause issues. The battery is around 3-4 years old, and multimeter showed it at 12.22 volts at rest.

When I google P0121 and P0222, they seem to be related to the throttle position sensor. But I also read here that 12.2 is low for the 12v battery and may cause issues.

I'm going to try pulling the battery and charging it, and see if it still has the problem. If it does, from brief googling, I couldn't determine if the TPS was something that was replaceable.

Thanks for any ideas/advice.

 

Ok I charged the battery up to like 12.8 when the charger said it was at 100%. As I held the multimeter leads on it, it was going down 12.80, 12.79, 12.78 etc. over the few seconds. A few minutes later I had it hooked up in the car, car behaved the same after 1 start attempt. The battery then measured 12.32 and dropping to 12.31 again as I was holding the leads on it.

So I'm going to hunt down a new battery for it..

 

Update, put a new battery in after charging it to around 12.9 volts. Same behavior

 

Do the error codes or symptoms bring anything to mind? I was planning to poke around the intake/throttle body area, not really knowing what I'm looking for, before having it towed somewhere.

I have a video of the engine starting up then rattling to a stop, need just one more post to be able to share the link.

 

Thanks Leadfoot. I looked this morning and didn't see anything off-looking, so I made an appt at the dealer service department. I'll go back out again and look more closely at the wiring.

 

Dealer says it's the throttle body. They said it'll be about 7 days to get the part. I didn't ask why it would take so long, but wonder if that's common. That something can't be overnighted or 2nd day from somewhere seem strange these days.

 

Got my car back today. Cost was $920 installed and it's back to its normal self again.