Why is my engine light on?

Honda accord 07 from dealership. Everything good but I got an oil change 4 days ago. Yesterday I had a thing come on the dash saying "check oil cap" I've read online about it saying that my filter might just need to be replaced by a Honda footer cause its tighter. I got an oil change from Walmart. Standard oil change. From 20% oil life to 100%. I'm not sure what to do. My engine light comes on now when i drive. Paid $42 for oil change. And they checked my lights and brakes and what not.

Did you by chance "check the oil cap"?

Auto parts stores can read the check engine codes for free, or they can sell you a code reader.

Umm… I think I'd start by checking the oil cap.

I know dealers are more expensive but a service is much more than just change the oil.
If you want you car to last either use a dealer or a specialist to service your car.
They would sort this for nothing after a service.