14591 - CUSTOMER SATISFACTION. CERTAIN VEHICLES EQUIPPED WITH A 2.0L 4 CYLINDER ENGINE (LTG) MAY HAVE A CONDITION IN WHICH PISTON DAMAGE COULD OCCUR DUE TO AN ENGINE PRE-IGNITION CONDITION. IF THIS CONDITION OCCURS, THE VEHICLE MAY PERFORM POORLY AND OIL CONSUMPTION COULD INCREASE. A WARNING LIGHT MAY ILLUMINATE INDICATING AN ENGINE MISFIRE. IF THIS REPAIR IS NOT COMPLETED BEFORE MULTIPLE PRE-IGNITION EVENTS OCCUR, THE PISTON MAY BE DAMAGED AND THE ENGINE MAY NEED TO BE REBUILT OR REPLACED. DEALERS ARE TO REPROGRAM THE ENGINE CONTROL MODULE (ECM) WITH A REVISED SPARK CONTROL CALIBRATION, INSTALL SPARK PLUGS WITH A COLDER HEAT RANGE (REQUIRED WITH THE NEW CALIBRATION) AND PLACE AN UPDATE TO THE SPARK PLUG PART NUMBER INFORMATION LOCATED IN THE “MAINTENANCE REPLACEMENT PARTS” FOUND IN SECTION 11 OF THE OWNER MANUAL. GM WILL MAIL THE OWNER MANUAL SUPPLEMENT TO CUSTOMERS OF RECORD.
