I took my 02 Passat 4Motion to the dealer for check engine light. The dealer said it is due to carbon deposit in the fuel intake, and on piston heads.
He gave an estimate of $5300 to fix it (along with a new timing belt, and a new water pump).
Dealer said if we have the piston heads fixed (send them to a shop to burn the carbon off) instead of replacing it, it would cost about $500 less.

Has anyone else run into this situation?

Thanks