2015 Tiguan CEL and Fuel Cleaner

Hey guys, I have a 2015 Tiguan and have had issues with a CEL. It was recommended I use a fuel system cleaner additive to remove the CEL, and it works after it goes through the system but only for a bit. The light comes on again after some miles are driven (not sure exactly how many but it's about 1-4 days of driving) and it stays on. When the light turns back on, there is a faint burn smell I get that dissipates almost instantly. Any ideas on what's happening?