2014 is the FB engine. There’s really no internal maintenance. Every 60k miles it’s recommended to replace spark plugs and perform an induction cleaning. Both relatively simple DIY work.
At this mileage, it may be getting close to needing valve cover gasket replacement. A little bit of a chow, but again can be done on a weekend day off. Pair it with spark plug replacement and knock out a twofer.
“Bad heater box”????? Sounds fishy.
Why would the car need a full exhaust? Is this something the dealer told you?
CarMax is only going to offer a low ball trade in value. Private party for your car is around $10k depending on your local market. It may go for as much as $12k down here.
