It seems like every time the car sits for a long period of time and then it gets driven, it throws the same code. I hooked it up to the scanner and it says "catalyst system below threshhold, bank 1". Is it getting a buildup in my cat from sitting around not being driven? Does anybody know what this means? thanks

 

It means the after-cat O2 sensor on the drivers side is not seeing evidence of the cat working correctly. Either the cat is contaminated, or the O2 sensor or wiring is faulty. Letting your car sit unused for extended periods of time will not affect the cat life or operation.