I took my 2008 Scion TC in to get smogged for the first time based on CA smog laws/rules in April 2014. The check engine light was on, so it automatically failed. I have a friend that works at a dealership & had him check my car out & the codes said it was showing up that there was a vap leak & he had me replace the gas cap. After changing this, the check engine light ended up going off. I had it re-smogged during the following week & again the smog technician told me that the codes were still showing up & still said vap leaks, even though the engine light was off. Thankfully, my car did end up passing smog after all, but I still don't know why or how there could be any leaks considering that I have the maintenance & stuff done like clockwork & my car only has 56k miles on it. This should really be something that Toyota looks into.

First off I am the first owner of a 2008 Scion TC and have owned the car for going on 6 years (purchased in 2007). I plan on listing all of the issues I have had with the car which really isn't that many. One day driving my check engine light came on and I went to my local Autozone to have it diagnosed. Not sure off the top of my head the exact error codes (you can probably google them) but it dealt with an issue of "escaping vapors." I took it into my local Scion Dealership the next day to make sure it wasn't something more serious and I was informed my gas cap was not on tight. Still got billed the $80.00 for them to tighten my gas cap. Fixed right? A few months have passed light came on again same codes. This time I checked the cap myself and realized the cap wasn't as secure as it used to be. I replaced the cap completely for about $10.00 reset my engine light (unplugged battery) and haven't had the issue since. My guess over time the seal on the gas caps become loose and no longer hold all the gas vapors within your tank which then triggers a sensor and sets off your check engine light. It is a very annoying issue but easily fixed.