No trouble code but intermittent Red Triangle

Hi Guys,
Seems like issues with my 06 prius battery are back, however this time it is rather strange but very predictable.
I cannot read any trouble code as the red triangle on the dash (and "problem" on the display) never stays on more than a few seconds (1-5 seconds at most).

at first it was doing this only after long downhill driving (like my 1.5 mile downhill street at 25 mph) - charging the battery and once getting to the last green bar I would get a Bip, red triangle and "problem" on the display.

this has been going on for 4 weeks roughly.

But it's gradually getting worse, the same symptoms would appear after shorter downhill driving. And now it does almost every time I get the foot of the accelerator (assuming the car has decent momentum to regenerate)

I am guessing a module is starting to fail but last time I had a failed block, it didn't do that. One day I got the red triangle along with a bunch of other lights and that was it.

I am logging all my trips with torque pro and custom PID's but I fail to see anything wrong in the logs.

I'm in China right now and my wife is driving the Prius and according to her it's gotten worse.

Other than for this, the car still drives fine with 41 mpg (we were down to about 30-32 when we drove with the failed block).

does anyone have any idea what this could be?

thanks
steve

 

oh wow
good to know - isn't there a oil pressure sensor and gauge or light?
thank you so much I will tell her to do that right away!

 

I mean something a little more explicit - like a oil level light or something.

thanks, I will start looking at the oil levels manually more often