I have a 2008 Toyota Highlander and accidentally filled the fuel tank with unleaded gas that has up to 30% ethanol. Will this hurt the engine (or just make the check engine light come on)?

30%? I have heard of E15 but never E30. If you really have E30 in your tank I would drain it. If it was just E15 don't worry but don't use it again.

E-30?, I would drive it and see how it runs. Then at 1/2 a tank I would top off with regular alcohol free unleaded if available or wait till 1/4 a tank and fuel as normal.

Thanks, F_O_R and Bob. I was able to reach a local garage where we take our cars for inspection and regular maintenance and they advised using up the 30% ethanol as soon as possible (such as taking a couple of drives to nearby towns) and then replacing with our regular fuel. I was also told to expect the car to run less smoothly and with less power than usual, and not to let the car sit (undriven) for a long period (like three days). Basically, I was advised to run it out.