2006 Toyota RAV4 engine check light

The check engine light, VSC light, and the 4WD light come on in my 2006 Toyota RAV4. I took it into the toyota service area and they told me that it was dirty gas and charged me $600, but the same same lights are coming back on. What is the problem? The car has about 40,000 miles on it.
Dirty gas would have absolutely nothing to do with VSC or 4WD.

Your first step is to have the computer scanned to retrieve the trouble codes that were set when the check engine light came on. Those codes will give you specific information about what the computer saw and will get you pointed in the right direction to find your problem. With a 1996 or newer and some 95 cars and you have an AutoZone or Advanced auto parts in your area, they will read them for free. Once you have these code numbers, we can be a lot more specific about what your problem may be.