With Multiple Wired engine mounts like on the V6, you can determine which one(s) are faulty using VCDS (even in shareware mode).
> Clear fault codes, start / rev engine fault should re-appear
> Disconnect engine mount sensors one at a time, clear fault codes, start / rev engine, and you will find with the faulty one disconnected the fault code does not reappear.
Other than this test, I have found no way to ID which one is bad. Cant see anything physically wrong with bad one.