What you are asking is if you should believe your Techs diagnosis. If you do, go ahead and change the part...
But I would never change anything until I had a positive diagnosis and I can not give you that without some info , like the codes ...
So, why don't you open the hood, push the button and get the codes.
That procedure is in the Archieves , so just search Code Retrive..
....and here are your codes ..
E320 16 PIN DTC Charts inc. pin 8, pin 14