I just had my 40,000 mile maintenance done 3 weeks ago on my 2001 Passat (4 cylinder turbo engine) and today the Emissions light came on. The display reads "Emissions Workshop!" I did discover that the gas cap was not closed tightly, and a friend suggested that it might have been the problem since the gas tank might be pressurized. How long before the MIL (Malfunction Indicator Light) will go off if there's really no problem (only the issue with the gas cap)?