[RyanY]

Before doing anything else, I would disconnect the neg battery cable to clear the codes, then reinstall and start the car. This way you will be able to tell whether you had an intermittent problem that caused the car to go into limp mode, or if it is something bigger that needs attention.

 

[RyanY]

Also, how many miles since the oil change 3 weeks ago? And did you do much freeway driving during that time? These symptoms can indicate low oil. IME the oil consumption is out of control with freeway driving in these cars - about 1 qt every 800-1000 miles. Be sure to keep it full.