The sensor mounted to the bottom of the big plastic cover under the windshield wipers is called an air quality sensor. Other than what the name implies, what does it actually do, and under what circumstances does it do it?

It's an electronic nose - it senses CO and NO2 in the air, and if the concentration reaches a certain threshold, it will automatically activate RECIRC mode on the HVAC system.

So when does this actually happen? Do I have to be in LA rush hour traffic? If you live in Kansas does it never actually do anything?

I've never had it happen to me that I know if, but that's what the owner's manual says it does.

Drive through smoke from a bush fire & it will trigger.

I love it when these three guys discuss Mercedes.

So, in the absence of a brushfire, how about a couple of mechanics smoking cigars? Actually, I suspect mine has never been triggered because if it isn't raining, and it isn't below 50F, I have the top down, which disables this.

@California: It's nice the have fans!

In the absence of a Socal wild fire I'm pretty sure a couple of well aimed puffs of cigar smoke would trigger it.

sorry to bud in but would my CLA250 2016 engine become “erratic” if introduced to hydrogen-oxygen gas through the air intake? i want to put in an HHO system but i seen somewhere that doing so the engine could become “erratic”. i’d like to know if this is fact. here’s what i read… “Some vehicles, especially newer vehicles with all the computer controls, could possibly run erratically if you introduce Brown’s Gas into the air intake system. This is primarily due to all of the sensors that are installed on vehicles today.

When Brown’s Gas is introduced into the air intake system, it enriches the quality of the air by adding hydrogen and oxygen. Vehicle engine sensors are designed to detect “normal” air quality and make any adjustments to the engine necessary if air quality changes. When they detect the hydrogen and oxygen enriched air in the air/fuel system, the computer will automatically make changes to the air/fuel mixture and cause the engine to run erratically.”

http://ledjournal.com/produce-your-o...gen-generator/