The weather in Denver, Colorado, USA is unusually cold, -10(F), the past few days and, unfortunately, my car isn't able to go in the garage at night at the moment. The past two days, upon startup, there are a lot of exhaust fumes inside the car, particularly when running the defrost. They go away after about 15 minutes.

Any ideas?

Obviously this can be dangerous.

Time to get the car up on a hoist and check for exhaust leaks, I reckon.

But....

Are you sure you're smelling *exhaust* fumes? If you have some oil leaks you might be getting fumes from oil (engine oil, trans oil, whatever) dripping onto the exhaust manifolds/pipes. It only takes a minute or two for the exhaust to get hot enough to burn the "drippings"....and give off quite a stench.

Cheers
DD

You may have an exhaust band clamp or a rusted pipe that's loose. The cold temps shrink the metal just enough to cause a leak. Get the exhaust system checked, you don't want to be breathing carbon monoxide.

Do you set the air recirculate switch on when running defrost? The exhaust can easily get pulled into the cabin if it gets near the outside of the windscreen. The defrost can be locked into recirc mode by holding the recirc button down for about 3 seconds when engaging it. You will hear a double beep. Took me about two years to discover that feature! I rarely use "fresh air" mode, to avoid exhaust fumes from my, and especially other, cars.

The outdoor temp display can be locked by this method too.