I am assuming you have a GM LPG. Fuel pressure in the rail is too high. Check your pressure - should be 12 psi - key on/eng off and 4-6 psi @ idle. Anything other than that, replace regulator.

Speed Sensor Out of Range High/Open (TCU):
DTC 522135-3 - TISS Speed Sensor Out of Range High/Open (TCU)
It is the transmisson input speed sensor. It is a three wire sensor on the trans valve. Most of the time it will either be a sensor, or if someone steam cleaned it, it will set the code.