I was experiencing a CEL on my 2017 KTM 390 fitted with a RB EVO Exclusive.
Bike has about 800 miles on it when i fitted the EVO and had no issues until about 1200 miles.
Would stall all the time when clutching in at stop lights and CEL would pop up after starting the bike and letting it idle for 10-20 seconds. My CEL i was getting was "o2 Sensor Low Voltage" or something like that. I would reset the CEL but it would always come back every other day. I ended up purchasing a used o2 sensor off ebay and when i pulled my old one i noticed the end of the sensor had white soot stained all over it (think the bike was running way to lean). Replaced the o2 sensor and reset the bike OEM learning map by letting it idle for 15 minutes and hook my laptop up to the RB EVO and reset the learning map on there as well. I have since rode the bike 300 or so miles with no issues so this has appeared to have fixed everything. Id say always reset your maps when you install new aftermarket parts so the bike can relearn so it can run properly.
"Burn Rubber, Not Your Soul, Baby." ~Smoke