I have the "service engine soon" light on. I was able to get the code: 1416 A friend of mine seems to think the air check valve needs to be replaced based on internet research. We replaced the one on the driver side, top, and cleared the code. After 3 months, the light came on again, and the same code popped up. Now I am told there may be 2 of these valves on the car. I want to know first off, what is code 1416, seeing as how my repair book does not list this code, and what do I need to replace?