Code P0715

There should be a switch that has a S and a C on it. It changes the way the transmission shifts. Example the S is for sport driving similar to city driving and C for long road drives. Check to see if the switch is good. Look at the dash and change from C to S with engine running standing still. The display should change from C to S. What that does it changes the way the transmission shifts, in S mode the transmission shifts faster than the cruise mode. Check the wires. Also on Mercedes it is usually the opposite of your problem. It stays in limp mode until the engine and transmission warms up. The code PO 715 refers to the supply voltage to the speed sensor. Check all the connections. Even though they may seem dry and clean, a little dirt can keep from getting good contact.