I had the same problem and was told to replace my O2 sensors. You have two O2 sensors and they are different, one upstream and one downstream. By mistake I got two cheap downstream ones instead of one of each. I let the mechanic source me the proper upstream one, but he had his doubts about the downstream one. Turns out he was right, as I still get a yellow check engine light about half the time. The light is currently off and I am curious as to how long it will stay that way this time. So, my recommendation is to get the right O2 sensors even if it they are more expensive.

 

Update: My check engine light has stayed off this whole time for some reason. I’m happy about that but I probably just jinxed myself and will get the engine light back when I drive the car tomorrow.