P0484 Cooling Fan Circuit Over Current code popping up

the Check Engine light has been on for over 5 days and the dealership said it was because of some small piece of dirty stuff in the cam tensioner. To fix it would cost around $2,400. However the tensioner is just a little device worth of $50, why they charge so much and is there a place I can fix it at a reasonable price?

tire infltion yellow warning light goes on occasionally despite correct tire pressure