at toyota they couldn't read the code as the light went out the day before the appointment,the car has 170,000miles on it,the put it on the diagnostic machine and told my wife it was the filler neck and the vacuum switching valve,I find this hard to beleive as we lost 10-15 mpg,it had the converted repaced at about 70,000miles and also the egr valve done about the same time .
Their explanation does not seem feasible. Sounds almost like they are wanting to throw parts at the car. Can we start at the beginning here? How are you calculating your mileage?