Jonathan Clayton

That is a great idea! We had a near total loss house fire in 2012 and the item that were able to be salvaged received an ozone treatment at the restoration company. Ozone worked wonders then but I never thought about trying it in the car. Thanks!

Benzie

After reading this thread - I would check the routing for how outside air gets into the vehicle. Maybe there's an outside air filter somewhere that's clogged up with pollen or other organic stuff. Anyone familiar with the fresh air system on this car?

Jonathan Clayton

Good thought! The only thing I can say for sure is that my smell issue is definitely weather dependent. It begins to smell as soon as weather warms in the spring and goes away in the cooler months. It makes me think that Audi is right with the "environmental" diagnosis (aka mold/mildew) but can't track it down.

Karl M

My 2017 A4 has a nasty odor this year that hasn't occoured before this year. Same as everyone else it is bad a few seconds after stating the car. It doesn't seem to matter whether AC is running or not. The smell is like fresh uncured silicone rubber bathtub caulk.
I tried a suggestion of running the car with vent fan on high and then spraying lysol under the hood where the cabin air intake vents are, and then turning on the AC and spraying more. Car smelled better of a couple days, but then the odor returned.