Catalytic Converter: Testing and Inspection

The symptoms of a faulty catalytic converter are:
Poor power output
Idle speed drops
Engine stalls
Rattle in the exhaust
The converter can be damaged by:
Engine misfiring (bad spark plugs, ignition wires, connections, etc.)
Ignition timing out of adjustment
Straining engine (pulling a trailer, mountain driving, etc.)
High speed driving at high outside temperatures
1. To inspect the catalytic converter, it is necessary to remove it from the car.
a. Inspect the ceramic grid inside from both sides with a light.
b. If any signs of melting, cracking, or breaking up of the ceramic grid are found, the converter must be replaced.
2. Inspect the ceramic grid for looseness.
a. Hold the converter vertically and drop it on its' flange from about 20 cm (8 in) on to a block of wood.
b. Turn the converter over and drop it on its' other flange from the same distance.
c. If a slight knocking sound is heard, or if the ceramic grid moves inside the housing, the converter is damaged and must be replaced.