Short life expectancy of aftermarket Catalytic Converters

[Jim Herold]

I have a 1987 190E 16v. I need to replace an aftermarket catalytic converter that has failed with only 1500 miles of use. The "biscuit" or "cookie" inside the converter can be heard rattling. This is not the first aftermarket converter that has had a short life on this car. In each case the "biscuit" breaks loose.

The car goes through the California emissions check every two years. It passes easily if the converter is good. It fails the test if the converter is bad--typically failing at low speed. (Calif tests cars under load on a dynamometer at a measured speed of 15 mph and 25 mph.)

The car has been thoroughly tested by a Calif licensed special facility. They welded a bung into the exhaust pipe in front of the converter and tested what was going into the converter as well as tail pipe emissions. All systems were good, including the oxygen sensor. Replacing the converter always solves the emissions issue.

My local independent MBZ repair technician says that in his experience aftermarket catalytic converters are notorious for lasting only 1-2 years on older 190 and 300 series cars.

I would appreciate relevant experience that anyone can share.

Thank you very much--Jim