That yellow tube is the wiring harness of the airbag. No, I don't think that's what people were referring to.My 2020 Mazda3 has this same annoying rattle. I have looked up under the glovebox and this is what I see. Am I right in thinking that the yellow hose is what needs to be secured and prevented from hitting something else? Where do I place the foam - is it up at the "other" end of the house i.e. as far as my fingers can reach? I guess I need to stuff it in so that there is no movement with the hose. Is that right? Any help / tips much appreciated!
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Between the two passenger air vents, there's a center vent. It appears fake at first sight, but if you look up into it, you see it has a small air outlet. There's a plastic tube (maybe an inch in diameter) going to it which is connected to the floor air ducts. I believe it's this tube that everyone is referring to.
The driver side has similar tubes going to the small air vents on either side of the steering column, though they do not appear to be prone to rattling.