How does the "smell" sensor actually work?

[jac]

That darn sensor (64116917001) has such a limited life span, I must have replaced it 5 times by now. :-)

So, I am contemplating replacing it yet again... And started to wonder about how it actually works. Does anyone know?

For example, what allows it to detect a bad smell? And what is its electrical signal/output when there is no bad smell vs when there is a bad smell?

[X5chemist]

From FCP : "Product Information
This clever little sensor detects the levels of oxidizable gasses flowing through the radiator. When a specific threshold is reached, the HVAC recirculation flap closes for a specific time after the noxious gasses are no longer present."

Apparently, it's an air temp sensor. If it's too hot, it closes the air flap.

[Henn28]

How do you know it has failed? Did it throw a code?

[getty150]

Originally Posted by Henn28

How do you know it has failed? Did it throw a code?

Good question...
From what I've read to understand is that a code is thrown..."auc 20" it's always there and that i should ignore it...and it can't be cleared.
I drive mostly with the no circulation button in the on position.
Just yesterday I found myself at the stop light behind someone with a blacken,smoky exhaust ...
No smelly fumes entered my e83 cockpit .

[Henn28]

Originally Posted by getty150

Good question...
From what I've read to understand is that a code is thrown..."auc 20" it's always there and that i should ignore it...and it can't be cleared.
I drive mostly with the no circulation button in the on position.
Just yesterday I found myself at the stop light behind someone with a blacken,smoky exhaust ...
No smelly fumes entered my e83 cockpit .

Thanks Getty - yep, I've had that code too for a long time. Haven't noticed a difference in the cabin, but I haven't really been paying attention. Couldn't hurt to replace the sensor though the next time I'm making an FCP order.

[getty150]

Originally Posted by Henn28

Thanks Getty - yep, I've had that code too for a long time. Haven't noticed a difference in the cabin, but I haven't really been paying attention. Couldn't hurt to replace the sensor though the next time I'm making an FCP order.

Yeah! I've replaced the sensor (got about 5 of'em)
I've opened it up and put in new filter stuffing.
I've only seen it work once...but I suppose that's because I commonly drive in air flow off mode.
But again you see my account I listed the other day on the road.
Cheers!

[Bdc101]

Originally Posted by X5chemist

From FCP : "Product Information
This clever little sensor detects the levels of oxidizable gasses flowing through the radiator. When a specific threshold is reached, the HVAC recirculation flap closes for a specific time after the noxious gasses are no longer present."

Apparently, it's an air temp sensor. If it's too hot, it closes the air flap.

Didn't the FCP description say it detects oxidizable gases, not temperature?

[X5chemist]

FCP calls it an air temperature sensor.

[andrewwynn]

FCP is wrong. It measures hydrocarbons in the air and the HVAC system will use that as input to decide to close off outside air for a few minutes at a time to block certain pollutants. I've monitored the sensor values when passing road construction and for example new asphalt will most certainly engage the automatic system to set recirculating air.

I guess the thing has a heater in it to work it's magic and the heater fails so it will stop working.

[X5chemist]

What are the units of measurement?