2008 Toyota Prius, intermittent check engine light

Hello! Thanks in advance for reading this long post. My 2008 Toyota Prius had a check engine light go on a couple months ago (when it was still cold weather), brought it to trusted mechanic, the code was for a leaky coolant valve, it was fixed, got it back, 5 miles later check engine light is back on. Brought it back to mechanic, code reads the same, flushed the coolant system out, light goes off, get it home, check engine light back on. Bring it back, mechanic drives it for 3 days, check engine light goes off, I get it back, 10 miles later it’s back on. As it’s getting warmer the check engine light goes off and on, seems to go off once the day warms up above 75. Coolant level hasn’t fallen during this time. Can I safely ignore it at this point?

If you could provide the actual code, that would be a big help.

Tester

it could be the coolant temp sensor, but the code would help

yeah, share the code, and then consider finding a different mechanic.