14151 - CUSTOMER SATISFACTION (MESSAGE ONLY, VIN LIST WAS NOT ATTACHED TO THE PREVIOUS MESSAGE). THIS MESSAGE IS TO ALERT DEALERS THAT GENERAL MOTORS HAS BECOME AWARE THAT SOME CUSTOMERS MAY BE OVERFILLING THEIR COMPRESSED NATURAL GAS (CNG) TANKS IN COLD WEATHER BY ADDING CNG BEYOND THE RECOMMENDED FILL PRESSURE. IF CNG TANKS ARE FILLED TO A HIGHER PRESSURE THAN RECOMMENDED AT A GIVEN AMBIENT TEMPERATURE, THEN MOVED TO A MUCH HIGHER AMBIENT TEMPERATURE ENVIRONMENT, EXPANSION OF THE GAS CAUSED BY THE TEMPERATURE CHANGE MAY CAUSE PRESSURE RELIEF DEVICES ON THE VEHICLE CNG TANK(S) TO RELEASE GAS, AS DESIGNED. IF AN IGNITION SOURCE WERE PRESENT, THIS COULD CREATE A RISK OF FIRE OR EXPLOSION. AN ADVISORY LETTER WAS MAILED TO ALL INVOLVED CUSTOMERS ALONG WITH AND OWNER MANUAL CNG SUPPLEMENT AND TWO LABELS WITH INSTRUCTIONS.
