SITUATION: A NOISE COMING FROM THE UNDERNEATH OF THE VEHICLE MAY BE EVIDENT. THE NOISE IS MOST PROMINENT DURING LIGHT THROTTLE AND LOW SPEED, FOR EXAMPLE DURING CAR PARK MANEUVERS AND IS INDEPENDENT OF AMBIENT TEMPERATURE RANGE. UNDER THESE CONDITIONS, A LOW-LEVEL NON-CONSTANT CYCLICAL-TYPE NOISE CAN BE HEARD COMING FROM THE CENTER EXHAUST SYSTEM (EXHAUST VALVE) ADJACENT TO THE FUEL TANK.