An illuminated Check Engine Light could be caused by a defective VVT-i controller, which changes cam timing for optimal power. Updated parts are available and the repair may be covered under the powertrain warranty.Google+
Car Problem Reports
Scion tC Check Engine Light Due to Defective VVT-i Controller
Scion tC Problem
Average Mileage: 105,795 mi (32,000 mi - 170,000 mi)
All lights illuminating after the battery light came on and 45 mins late no steering no acceleration and finally no power!!! Not fixed because no one will give me any answers aside from taking advantage of me because I'm a female and I've been told everything from the serpentine belt to the crankshaft pulley to the voltage regulator and the alternator then the timing belt!
Visitor, 2006 Scion tC, 170,000 mi
My car turn on the engine light when the gas cap is loose. I had to change the cap and the light turn off about 2 weeks later. Now I had the same problem... I check the gas cap again... it looks good.. but the light still on. Don't know what to do now...
Visitor, 2006 Scion tC, 80,000 mi
My check engine light comes on whenever I start the car and begin to drive right away. I think it's reset after a few times of starting the engine and letting it sit for a few minutes letting the idle drop to normal before beginning to drive or even touching the gas pedal. Sometimes it's worse than others, like when the idle keeps going up and down when I am stopped at a light or something and also has stalled when I come to a stop and the idle falls too low. It's not a good fix because it keeps happening and I now have 190,000 miles on my car.
Visitor, 2005 Scion tC, 95,000 mi
Scion suddenly stalled 1 day while coming to a stop since then my check engine light has stayed on even after cleared. when hooked up to a scanner three diff. evap codes come up. I've also replaced my gas cap but still idles rough other than the first start of the day. Usually dies when I come to a stop or after starting it again after it has been driven prior too. I was told it could b iac valve but dnt think my car has one of those. No solutions or answers yet
Visitor, 2005 Scion tC, 105,000 mi
Ligt comes on contstantly after run the car for between 136 nd 236 miles after odometer reset
Rough idle, high acceleration noise. Need to repair, just happened.
Visitor, 2005 Scion tC, 32,000 mi
dash lights have been on for quite some time. Had a mechanic look at it and was told the camshaft gear assembly needs to be replaced at about $700.00.