I know everyone keeps saying this, but I’m noticing the same problem. I’m driving my sister’s 2014 Cadillac SUV and the check engine light goes away with full tank. There were about 4 error codes she told me when she failed emission last week. The ones I remember her telling me were P0171 and P0174. Another ending is P0…14 (ended in 14). Anyways, While the light was off after i filled the tank, I ran and got emissions on it and it passed.
I have the same thing with a 2010 Rav4. For about a year now. Goes off after every gas fill up. Not a coincidence. I replaced the cap but that wasn’t it. I wish someone would post if they had success solving this.
begin a new thread here, and maybe we can help. Be sure to list Year, Make, Model, engine, mileage, engine diagnostic trouble codes, and any recent repairs done in your post. That will be a lot more effective than tagging onto the old post about a different vehicle. 