Defaulting to second gear is "limp mode" which allows you to drive slowly to a repair shop without needing a tow truck. You already know that you get it out of limp mode by turning off the ignition switch and restarting the engine. When this occurs, it is in response to the Transmission Computer detecting a problem. In this case it is most likely to be related to one of the speed sensors, but to know for sure, the place to start is always by having the diagnostic fault code(s) read. Fault codes never say to replace a part or that one is bad. They will indicate the circuit that needs further diagnosis or the unacceptable operating condition.
Wednesday, December 17th, 2014 AT 6:13 PM