What Exactly Is Limp Mode?
"Limp mode", also known as fail-safe, has been engineered into the electronics that control your automatic transmission to allow the vehicle to be driven, at slow speeds, home or to a repair shop. "Limp" occurs when the computer has detected a problem in the electronic control circuits or has detected an actual mechanical problem within the transmission. Instead of leaving you on the side of the road, the computer commands second gear so it can still be driven 25 to 35 miles per hour.
If a light starts flashing and you can't feel the transmission shift, the computer may have placed your transmission in 2nd gear (limp mode) pull off the road and turn the engine off for a few minutes. This might clear the trouble code so when you restart the engine, you can drive normally until "limp" occurs again. If it does not clear "limp" and start shifting normally, it will be time for a trip to your trusted transmission expert to see if it is a problem with a sensor, wiring or an actual mechanical problem.