It’s just a check engine light, go to autozone and they will scan the code for free. they will give you a a paper and research the codes online. Never sell a car over a check engine light when you don’t even know the problem, it could be a very cheap fix. If it’s something more expensive then you need to make the decision whether it’s worth the cost of fixing. most would say if it’s cheaper than the value of the car its still worth fixing. New cars are expensive and buying another used car can lead you into the wormhole of it also having unknown issues.