Is the car misfiring? the code you have is specificaly :P1494 Leak Detection Pump Switch or Mechanical Fault
The leak detection pump puts the gas tank and emissions components under two pounds of pressure while you're driving, then a sensor watches two see if that pressure leaks down. If it does, as in when you don't tighten the gas cap, a fault code is set and the Check Engine light turns on. That fault code will indicate a small leak or a large leak. The code you have indicates that pump is not building pressure at all. Either what controls the pump has a problem or the pump isn't running. That system won't cause the car to stall, but the Check Engine light will be on. If the pump is broken, gas will evaporate out causing emissions and reduced fuel economy. The Check Engine light is required to turn on when the detected fault could have an adverse affect on emissions.