this is for a 2003 x-type, I recently change spark plugs, valve covers and upper intake manifold gasket, the car was working good before replacing what I mentioned, I also replaced the transmission fluid.
I turned the car on and it stared right up, I warmed the car up lifted to check the fluid level it needed close to 2 quarts and after adding the last fluid, I told my son to shift the car from P all the way to 2, as soon as he shifted to R I started to hear a vibrating noise on the transmission, you could actually feel a vibration on the transmission cover, I went to test drive the car and it shifts normally but the noise doesn't stop unless I put it on P.
also the check engine came on and the code that comes up is P0020, I don't think that they are related but I don't know.
any suggestions?

 

update on the issues code P0020 has been resolved, it was a connector that wasnt propperly connected.
I still have the issue with the transmissionmaking a vibrating noise, the noise starts as soon as i shift to Reverse, the car doesnt have to move, the noise continues when i shift to the other gears and it only stops when i put in Park.
could it be related to using a different transmission fluid?