2010 Toyota RAV4 check engine light

The CHECK ENGINE light and the 4WD light are on. nothing seems to be working improperly. a mechanic changed some device, but they are now back on.
Is this a common problem?, does it indicate a problem with the vehicle?; how can it be fixed?



Without knowing what code(s) turned the Check Engine Light on, it’s impossible to say.

If you don’t know what the original codes were or what the new codes are now, who knows if something was misdiagnosed or if it’s a new problem altogether