I own a 2001 Toyotal Echo and first had a "Check Engine Light" on back in June 2009. When I brought the car back to the Toyota dealership, the printed report indicated:
- Cause: P0440 - Evaporation emission control system malfunction monitor information. Failed purge VSV.
- Correction: Checked purge VSV - working fine at this time. Cleared codes. If come back, will need to re-test purge VSV and replace purge VSV.

Around January 2010, the "Check Engine Light" reappeared. Again, I brought it back to the dealership - but I waited until early April 2010 to do so (owing to a lack of time!). This time the report indicated:
- Cause: P0440
- Correction: Cleared code. If comes back on, recommend replaced charcoal canister with VSV.

In less than a few weeks, the "Check Engine Light" came back on again for the THIRD time in late April 2010. I have yet to take the car back to the dealership, as all this is incurring significant costs. Meanwhile, I have tried tightening the gas cap (I take this to refer to the "fuel tank cap"? Please correct me if I'm wrong!)

Could someone please advise:

1. If I need to take the car back to the dealership for the THIRD time?
2. From the description provided, in non-tech lingo, what appears to be the problem?
3. Would you recommend getting BOTH the charcoal canister and purge VSV changed? (Especially, given the age and value of the vehicle. The car now only has about 32,000 km on it.)
4. What would be the anticipated costs of having either or both the charcoal canister and purge VSV changed?
5. What would happen if I do nothing - is is harmful/dangerous to drive a car with this problem? (I'm more concerned from a safety perspective.)

Thanks very much!!!