CarTalk.com Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

White odorless vapor from exhaust of 2009 BMW 328i

Greetings. I just bought a 2009 BMW 328i with 7000 miles on it. Beauty of a car. Seems to drive great. Today though, I noticed an odorless white vapor coming from the exhaust, but nobody else on the road seemed to have anything coming out of their exhaust, so I worry something’s wrong. No sweet smell. In fact, there is NO smell. Interior of tail pipes seem damp. It’s a little chilly, and I assume this is steam. Is it a problem? Should I get it back to the dealer? Any thoughts, knowledge about this issue? THANK!

Sounds like harmless steam from combustion, bet it goes away when it gets warmer. Do check your radiator fluid frequently, just to make sure.

It’s normal for some moisture to condense in the exhaust system. Water vapor is a byproduct of combustion. As the exhaust system heats up all of the condensed water from the day before will be expelled out the tailpipe or evaporated as steam. Nothing to worry about.

You don’t see this on the road because it only happens at cold start-up and it goes away shortly after.

Thanks McParadise! Much appreciated.