I failed an emissions test, What do I do.

A header is the part of the exhust that connects from the exhust ports on the motor to the catalytic converter.yep thoses things go wrong and the converter will stop up , making the car run foul smelling and not run good , and your header pipe is bad id say to , but keep the old converter its got a really rich amount of metal in it , and if you take it to the metal scrap yard , they pay from a 150.00 to 200.00 for them , because of the platium in them , so dont let them keep it , you sale it and get some of your money back , the converter, has gray pellets in there , that collacts exhust , and carbon builds up and stops up the exhust, so hope this helps