Is my car a lemon

So back in December I bought a 2017 Ford Fusion from a dealer for 16k with 29k miles. It was a good car at the time other then a small chip in the paint on the front bumper. The car had previously been a lease car. And now 5 months later. One of the wheels has a squeaking noise and the check engine light comes on and off. I brought it back to the dealership as they were offering to buy it back. They only wanted to offer me 15k for it and I still owe 17k on it from my previous trade in. Does anyone think it’s a lemon or what should I do. I honestly think it shouldn’t be having problems at such low miles. But I don’t know much about cars. Any help?