Jumped off the highway today, hadn't pushed the car at all. Waiting at a traffic light I noticed some smoke or steam coming from engine bay. Temp gauge was fine and couldn't find any evidence of a leak under the car or the hood. 2016 S with 30,000 miles.

 

Was it raining? Did you drive through any puddles? Water hitting the hot exhaust manifold can create steam.

 

If it was raining it's likely water evaporating. If it wasn't, then that is rather strange. I don't think AC condensation hits the exhaust pipes, however if it does, that could be the cause for the steam. I run my AC everyday, and haven't noticed any steam coming from the engine bay when I'm at a light. Living in SW Florida, plenty of humidity being pulled from my cabin too.

I'd probably let it go for now and keep an eye on it. Generally if you have a radiator leak or engine overheating issue, you'd pick up a smell in the cabin. W/ gauges reading fine, likely not happening unless that sensor is bad..again unlikely.

I have a pretty good relationship w/ my dealership service manager, so I wouldn't be afraid to call my guy and just ask the question to put my mind at ease. If he thought it was something to be concerned about, he'd tell me to bring the car in.

 

My guess is the water also and the radiator might had some water on top of it puddling, there some foam pieces that light to catch rain and then steam if off.