The check engine light came on with the code P2181 but the coolant level is good

What is your question?

My check engine light came on with the code P2181. The guy who checked it out said to check the coolant level and he turned the light off. When I checked the coolant level, its fine. It's not below the minimum line at all. Could the problem have anything to do with my transmission? Because I do know that my transmission fluid needs to be changed.