Temp sensor failure-okay to ignore?

Forgive me if this has been asked before but I can’t find anything exactly the same.

My engine light came on, and I brought it to my mechanic who took the codes and told me that I had a faulty temperature sensor for my hybrid battery. I can’t remember the exact code but he showed me the screen and it said “temperature sensor failure”

it’s running perfectly fine, keeping a charge and I get ~40mpg doing mostly city driving.

He didnt have the part, and I moved and kind of forgot about it for a while. Finally called the dealership who said they could order the part....but because they have to open up the hybrid battery the labor will cost ~$1200, which doesn’t even make sense to spend on such an old car.

The light has been on for 6 months and I’ve periodically checked the codes to make sure that’s the only one it’s throwing, and I still don’t have any issues with it running. But I’m driving ~600 miles up the state next week so I’m a little worried if it could cause problems.

thanks for any advice!