# Marshmallows?



## Podsnap (May 26, 2010)

My 335d (1250 miles) is running on high and smells like a burn marshmallow. Is this the DEF burn-off? It's in my garage now and turned off but the fan is still going a half hour later.


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## dunderhi (Dec 10, 2006)

I would guess so, the burn-off should happen while driving under a light load, but maybe the fan stays on to cool it off. I've noticed the fan running after I stopped the engine, but I never hung around to see how long it stayed-on.


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## bimmerdiesel (Jul 9, 2010)

seems like its ur first post here. congrats and welcome to d club

About smell some say its marshmallows.. some say its scented baby diapers some say burn smell... all I know is it is DPF (not DEF). 
Fans typically stay on for a while in 335d for various reasons : diesels work on higher temps/ car is in btw DPF cycles

I once parked in friends' heated garage overnight and next day he was complaining of marshmallows smell in his garage :rofl:


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## Hu99 (Aug 29, 2010)

Check your hot chocolate reservoir. If the level is too low the marshmallows will burn.


I'm sorry, I couldn't resist.


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## Podsnap (May 26, 2010)

Just as long as I don;t get anything 'smore.


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## dunderhi (Dec 10, 2006)

bimmerdiesel said:


> all I know is it is DPF (not DEF).


Oops, I didn't catch that.


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## 5SeriesNatsFan (Mar 8, 2010)

I have experienced both fan run-on and a burnt smell too, but not at the same time. Both went away after a time. IMHO, these things are the normal, if occasional, part of vehicle operation and are nothing to worry about.


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## Penguin (Aug 31, 2003)

Sounds like the particulate filter burn-off (DPF), as many describe it as a burnt sugar or caramel smell, which sound pretty close to burnt marshmallow. The DEF (Diesel Exhaust Fluid) is injected into the exhaust before the nitrogen catalyst and doesn't have a smell after it goes through the catalyst.


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## TDIwyse (Sep 17, 2010)

Hu99 said:


> Check your hot chocolate reservoir. If the level is too low the marshmallows will burn.


HA! About spit my coffee on the monitor when I read that.


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