Check Engine Light after using Fuel System Cleaner
BLUF: If you are certain your check engine light came on due to you adding fuel system cleaner, don't worry about it. It will turn off after burning through a tank or two of gas.
I own a 2017 Thor Freedom Elite 30FE with the Ford V10 E450 powerplant. After a length trip and roughly 30 tanks of fuel I decided to add fuel system cleaner in case I had any dirty fuel in my system. Shortly after adding it my check engine light came on with the P0174 code (System Too Lean Bank 2).
After this happened I read that it was a common occurrence. I was going to drop the MH off to have it checked for warranty service, but couldn't get in for a few weeks. I had a week long trip planned and decided to live with it for now. I ended up running to the closest place for propane and on the way the light magically turned off and never returned. It was on the next tank of fuel (without fuel system cleaner additive) that it burned off whatever the sensor didn't like.