2008 prius p1150 and p1151

my prius intermittently displays the red triangle warning light and the engine overheating warning on the dashboard. The problem is very random. Sometimes I can drive the car for a long time without any warning lights appearing, while other times the warnings come on after just a short trip, such as driving to the store.

In some cases, the red triangle and overheating warning appear without the check engine light. Other times, the check engine light also comes on along with the other warnings.
yesterday engine light came up with P1150 and P1151
From what I've found, there seem to be quite a few different parts that could cause one of these codes. I'd like to narrow down the most likely cause before I start replacing parts.

I haven't been able to find much information online about these two codes appearing together. Has anyone experienced this combination of codes or have any ideas about what I should check first?