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      10-15-2019, 02:38 PM   #1
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Drives: '19 Mineral White X5 40i
Join Date: Feb 2014
Location: Houston, TX

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Exhaust smell at cold start

So, if I get in the car ('19 X5 40i) and start it when cold there's a whiff of exhaust while the engine warms up. If I run around to a few different stores I won't smell it at each of those starts from warm. However, the next cold start will do the same thing. It's the same smell you get if standing behind the vehicle when it starts. At first I thought maybe I was starting it before I closed my door but even with making sure it's closed before starting I still get it. If I remote start and wait, the smell has mostly dissipated by the time I get in.

I reached out to my SA to bring it in, but wondered if anyone else has experienced something like this. Thank you!
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      07-14-2020, 04:32 AM   #2

Drives: 2020 X5 M50i
Join Date: Sep 2019
Location: American in Belgium

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It's normal when cold-starting to run an extremely rich fuel mixture. That helps the car warm up to operating temperature. Similar to using a choke back in carburetor days. It's not uncommon to have a fuel smell OUTSIDE the car when cold starting.

inside the car however.... you should not smell it. If you do, it's possible you may have an exhaust leak.

If you have an exhaust leak that you can smell inside the car during cold start.... then you still have an exhaust leak inside the car that you CANNOT smell during normal operations. Fuel has a smell.... Carbon Monoxide does not. If it's leaking into your car when you start it..... it's still leaking into your car under normal operation.... you just can't smell it as much.

Take it to the dealer and have them thoroughly check for exhaust leaks. They can be dangerous, and even cause you to pass out while driving if left running for too long. If nothing else, you're likely to get headaches that you can't explain.
2020 X5 M50i - Alpine white, Coffee, Lux seat, poplar, Executive, 21", shadowline, Towing, air susp, Bowers & Wilkins, Acoustic glass, *CD player*
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      08-22-2020, 02:36 AM   #3

Drives: 2020 x7 m50i
Join Date: Nov 2011
Location: so cal

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if you're smelling it inside the car with everything closed, you may have a leak somewhere. smelling this outside is perfectly normal because your catalytic converters don't really work efficiently until they're hot, so when cold they won't catch and burn/react off everything.
2020 bmw xHippo, v8tt edition
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