The catalytic converter is now standard equipment on all vehicles sold in the United States and Canada and is mandated in most states and provinces. The catalytic converter is a smog control device attached to the vehicle's exhaust system to filter out particulates and some chemicals that would otherwise be emitted into the atmosphere. The catalytic converter gets its name because it uses a catalyst (or group of catalysts, actually) to capture and convert specific molecule types so they are not sent out the tailpipe.
The converter looks similar to a muffler and usually resides either immediately on the exhaust after the manifold (common on front-wheel drive vehicles) or about halfway down the exhaust pipe somewhere in the center of the vehicle.
How To Tell if the Catalytic Converter Is Not Working Properly
Usually, the catalytic will become clogged, causing the vehicle to become sluggish, idle roughly, and sometimes backfire or sputter. Often, when severe, this clog will choke the engine and prevent it from speeding up or quit altogether. The most common catalytic converter failure, however, is leakage due to rust and corrosion or impact from something bouncing up from the roadway.
If the vehicle "tractors" or makes loud exhaust noises, then the leak could be anywhere on the exhaust line including the catalytic converter.
Repairing the Catalytic Converter
Most of the time, because of the laws surrounding them, home mechanics are now allowed to do much with a catalytic converter other than remove and replace it. Repairs can include patching holes in the pipe connections or body of the converter, but internal repairs are not legal.
Disposal of the cat is another problem, since these converters are heavily regulated at the federal level. They do have value for recycling, however, so a junkyard or recycler is your best option.
Be aware that some older catalytic converters utilize asbestos as a filler and so can be dangerous to handle if brittle.
Originally utilized to reduce toxicity of emissions from internal combustion engines, catalytic converters are most commonly used in vehicle exhaust systems. They are legally required in many places that have regulated emissions standards.