General Motors bulletin. It is actually PIP3081 which states, "SES Light and P0300 When Towing , Cruising Uphill or on Hard Acceleration - kw 4.3 5.0 5.7 accelerate cruise cylinderhead DTC L30 L31 L35 LF6 LU3 P0300 P0301 P0302 P0303 P0304 P0305 P0306 P0307 P03... Login to read more.