When transmission is in D at speeds over about 55 it will bump back down into 4th gear (i can change to S4 and rpm's don't change). After another 5 minutes the trans will go into limp mode with dreaded red gear lit up on dash. Also the check engine and dcs light are on and stay on. Turning car off and back on will reset the limp mode and the red gear light will go off. The car can be driven in S4 and never have any problems. The codes have been scanned and read, "Error code 0x37 (55) Gear check 5> No DTC detected at time of request." This is a 2000 e46 with the GM trans.