had a famous P0471 code along with 3 errors of side sensors. I read that they usually come together.
had it twice within two weeks.
started researching. All comes out to 3 things. ATF, TCC solenoid, or the TCC itself. Decided to do only what I can do myself, that is change the ATF 3 times as per TSB for 2013-2017 ( strangely 2018 was not included) . So far, so good.
My question is: after changing the ATF I noticed the car runs much smoother, mileage improved too.
could it be that all these errors due to ATF being old?

 

Having bad ATF fluid could certainly trip a bunch of codes if your transmission is running bad. Make sure to minotor it just in case there actually is an issue with your transmission, although it sounds like there isn't.