Seamus, You've experienced "LIMP" mode. It could have just been a fluke. IME I have just shut the car off and it reset it. If it were to stay in LIMP mode, you would be able to drive it at no more than 50 MPH for 50 Miles (or so they say). To a point where you can oull the TCU codes to see "why" it's in LIMP mode. Good Luck. Scott P