Hi Guys. Im new to the forum so sorry if the question has been asked before. My '02 x5 4.6is engine light is on and the codes read p0491 and p0443. I took it to the stealer and they told me that there's carbon build up in the heads and that one of the banks is holding 40 PSI of pressure. To fix it they said they would have to pull of the heads and clean them manually. The car runs and drives fine lots of power. No issues. ANy idea if they are trying to take me for a ride? should i try something else? Any suggestions would be great. Thanks