This Preliminary Information communication provides information to the technician about vehicles that may be running rough with a Malfunction Indicator Lamp on. Technician may find Diagnostic Trouble Code P0300 set. Technician will need to perform an Engine Compression Testing in Service Information. If excessive leakage to the crankcase is isolated, check piston and cylinder wall condition. Technician should perform the repair per the level of damage. If the cylinder wall surface has not been compromised, only piston replacement is required.
