Told My Friend To Not Worry About His Half Plugged Catalytic Converter On His Mercedes

[DanieRains]

Since this is Seattle, it will be stolen soon enough, and then he can get a new one.....

[ProfessorGAC]

1. Half Plugged? Unsure What That Means

That's a bad break!
Clogging is about the 5th most common cause of catcon failure.
Coating of the substrate is #1. The air still flows, but the oxidation reactions don't take place, so it becomes no more than a fat spot in the pipe. Usually caused by valve or ring issues sending lubricant oil into the converter. Causes no clogging.
#2 is a collapse of the catalyst structure. That could cause flow restrictions, and that might be what "half-clogged" means. The causes listed are external impact or inefficient combustion, which causes raw fuel to hit the converter. Makes it really, really hot and causes to ceramic structures to embritlle or break.
But, a straight clogging is pretty rare.
Your friend is likely staring down a $1,200 repair. Bummer!

[WHITT]

2. Time For The Seinfeld Move