Jennifer,

That looks like the little plastic water guard that is attached to the vent on top of the tranny. Transmissions develop pressure as they heat up so MFGs put a vent hole on top. Have this reattached by your mechanic, but I suspect it is broken and needs to be replaced. If you ignore it and don't have one installed, you run a great risk of getting water in your trans during rainy weather or when washing the car. This is not a good thing. It could cost you a couple thousand dollars.

Peter

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