Help identifying this part? 2006 325i-automatic

[sabresfan]

I developed a leak in the tranny. Gasket seems ok. This hard plastic part appears to have lost its seal. Any help? Is this a huge, expensive fix?

[relative4]

That is the Valvetronics sleeve. It's like a $17 part, but to replace it you have to drain the oil and pull the pan. The fluid is about $150, and while you're at it you should replace the pan because the filter is integrated. So the whole job becomes kind of expensive. And then, while you're in there you should also replace the seals between the valve body and the transmission, cause when (not if) those go, you have to do the whole job over again.
It's not too hard a job, but you have to carefully read and follow the instructions for filling the fluid to the correct level.

[sabresfan]

Thank you!