Fuel or oil deposits build up on the surface of the converter. The engine could be burning oil but you wouldn't know it as long as the converter is functioning properly. But additives in the oil will eventually destroy the catalyst.
There can be a few reasons for a catalytic converter to go bad. One of the causes could be clogs. Other reasons include plugs not working right, and bad exhaust valves.
A catalytic converter should NEVER go bad unless something causes it such as a RICH or a LEAN condition. What is a "RICH OR A LEAN CONDITION"?
A bad coil can damage a converter. If the engine is misfiring, it will cause raw fuel to get into the converter and that can cause failure.
They can become clogged or they can burn out.
Yes, the unburnt fuel from poor timing will enter the converter and slowly destroy it.
If the cat goes bad you will notice a large reduction in fuel economy, and it causes your vehicle to produce a lot more emissions. This may also cause your oxygen sensor to go bad and possibly your EGR valve as well.
Yes. If a coil is bad causing one or more cylinders to not fire, this allows raw unburned fuel to enter the catalytic converter, where it is burned. This can ruin a converter.
It can, you may also have misfire codes as well, having a bad cat causes all sorts of issues. There may be an underlying issue though because unburned fuel ( hydrocarbons ) is what causes a cat to go bad in the first place.
No, the catalytic converter is downstream from the EGR valve so it has no effect on it.
The hub bearing can go bad and create noise.
It is possible but highly unlikely.
the shop I go to said that my 2000 Jetta would not pass the smog check when the catalytic converter went bad.