'Check engine' light back on despite new gas cap.
on 2004 Toyota Echo

Although I am located in Toronto, Canada, it would appear that I have a similar problem to other queries.
On May 22, 2012, 104,000 km service performed (actual mileage 103,206)by an independent garage. Engine light on June 5th; computer advised problem due to code EVAP. Gas cap tightened, system reset; light off.
Thereafter, I have returned 4 times (gas cap seal reversed, rust removed from gas tank intake,and finally, a new gas cap was purchased). Invariably, the engine light would come on again 2 to 3 days after refueling. However, the last time the light came on was 2 days after the system had been reset. I am now being advised to go to a Toyota dealership and that I may be facing a bill of $3 - $400.00.
Was also advised to simply ignore the engine light being on; but of course this may eventually mask another problem.
Before consulting a Toyota dealership, I would appreciate any and all advise inasmuch as I was once advised by a dealership that the clutch was leaking oil and that the repair was urgent. A second opinion was sought; no problem found and I drove the car for another three years without any oil leaking from the clutch.

1 answer 1 comment
have a smoke test done and diag of issue. you may still have a small evap leak that is undetected
As advised by another correspondent, I finally went to a Toyota dealership about the problem, insisting that first and foremost, all the hoses be checked.
Sure enough, "the vacuum hose from the air box was loose". It was "re-installed and the codes were cleared.
Had this work done on September 24th and to date, the problem has not returned.

As a result of the advice received on RepairPal, I was only charged for a half hour of labour - $55.00. A
smoke check would have cost approximately $110.00 - $165.00!!!!!!

Thank you, thank you!!!!!!!

Why22Kay in Toronto, Canada.
P.S. Vote for Obama; remember that his policies and actions affect me - your neighbour!!!!!!!