You NEED to heat it with a blow torch. When you heat it, you combust the deposits. Combustion of the deposits lessens the mass of the deposits to a very low ratio, as most of it goes up in smoke. But if you don't wash out the combusted deposits, you just basically wasted your time. Simply spraying with a brake cleaner won't do anything.

Go to your local hardware store and buy a regular butane torch. They are bout $10-20.

To reset the check engine light, head to volvospeed.com, and head to bay 13 for instructions with pictures.