2023 kia rio using a lot gas

Well , you did buy a crappy car so yeah , it may be a lemon . Good luck at the dealer or with any litigation .

You should be getting around 33 mpg. There is a problem, and the dealer needs to fix it under warranty and provide a loaner when it's in their shop for more than a day. This is how it goes sometimes with Korean cars. Give the dealer three tries to fix it, and if he can't, and you're in a Lemon law state, you get a new car.

Take it back ASAP and don't let them feed you a line of it's not broke in or that's normal for the first 1000 miles. document everything just in case this gets messy.

I took it and they said no codes or fuel leaks. What else could be the cause?

Fuel trim too rich, leaking injection system, engine running too cold a bunch of stuff that they probably don’t want to check cause it’s under warranty, keep at them, tell them you want results. There should be a phone number in the back of the owners manual that you can call main customer service if your dealer is not following through.

Thank you GA. I seen the posting through my email. I'm going to try that.

Good Luck and keep at them.