Nine Ways to Kill a Cat
A leading role in the reduction of harmful exhaust emissions is the catalytic converter, through which exhaust flows on its way to the atmosphere. The lethal components of exhaust gas are rendered harmless by the converter. This device should remain effective virtually forever unless it's damaged.
Its enemy number one originally was the lead in gasoline. Now, however, with all gas lead-free, nine other factors have become infamous as "cat killers".
Periodic checks and maintenance will disclose most of these discrepancies, which Car Care Council lists as "the nasty nine". The first three are critical sensors in the emissions control system: oxygen, coolant temperature and throttle position. If one or more of these sensors send the wrong information to the computerized fuel, ignition and/or emission control systems, unburned fuel in the exhaust will damage the converter.
Culprits four and five are a leaking fuel injector and ignition misfire, such as one or more worn spark plugs.
The next three are less common, but worth noting: bad gas, a leaking head gasket and a faulty fuel pressure regulator.
Finally, and not necessarily least common, is oil burning due to worn engine components. Oily exhaust can ruin a catalytic converter. Car Care Council points out that even the most advanced vehicle design still demands periodic and maintenance service.
[This article was reprinted with permission of the Car Care Council]