Q: 2005 Cadillac CTS 3.6L V6 having transmission issues

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I have already asked a couple of questions on here regarding this vehicle that I purchased within the past week and this is more of a follow up to the last question I asked regarding a whining noise when the car is at 30mph and 1500 to 2000 rpms. I received an answer about the noise, saying it was transmission related, but I have a follow up question if that's possible. This noise wasn't noticeable a week ago and the check engine light also wasn't on when I purchased it. When it was hooked up to a computer, I was told it had a code of Po430. Is it possible that the whining noise is causing the code, or is that a completely separate issue? The whining stops after you exceed 30mph or 1500 to 2000 rpms. I'm just wondering if it's possible that the code could be connected to the whining noise or if I have two different problems. If so, then I need to decide if I want to actually keep this vehicle or sell as is and not keep sinking money into it. I appreciate any advice if possible.Thanks

My car has 144000 miles.
My car has an automatic transmission.

The code P0430 is for the catalytic convertor or the sensors for the catalyst is having a problem. This may be from a bad catalyst or a defective sensor. Most likely this code was already there and the last owner just cleared the code, since it may take a week or two of driving for the code to return. As far as the transmission problem the code has no relation to the transmission. I suspect the last owner may have put an additive in the transmission that may have keep it quiet for a few days or you may have just not noticed the noise when purchased. Have a transmission mechanic listen to noise to confirm my diagnosis I gave you before as and internal bearing or planetary gear set is going bad.

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