Tracker 2WD L4-1.6L VIN 6 (2000)
Catalytic Converter: Testing and Inspection
Catalyst Monitor (Bad Catalyst)
Catalyst Monitor (Bad Catalyst)
A degraded, or bad, TWC catalyst, 65 percent hydrocarbon conversion, will show greatly increased activity in the output voltage from the post-catalyst
heated oxygen sensor (2). The degraded catalyst post-catalyst HO2S output voltage will therefore appear similar to the typically active output voltage of
the pre-catalyst heated oxygen sensor (1).
Catalyst Monitor (Good Catalyst)
Catalyst Monitor (Good Catalyst)
A good TWC catalyst will show a very active output voltage on the pre-catalyst heated oxygen sensor (1).
A good catalyst, 95 percent hydrocarbon conversion, will show a relatively flat output voltage on the post-catalyst heated oxygen sensor (2).
Catalyst Monitor Diagnostic Operation
The OBD 2 catalyst monitor diagnostic measures the oxygen storage capacity of the 3-way Catalytic Converter (TWC). Heated oxygen sensors (HO2S)
are installed before (pre-catalyst) and after (post-catalyst) the TWC. Voltage variations between the sensors allow the PCM to determine the performance
of the TWC catalyst. When the TWC catalyst becomes less effective in promoting chemical reactions, the catalyst capacity to store and release oxygen is
generally degraded. The OBD 2 catalyst monitor diagnostic is based on a correlation between the conversion efficiency of the TWC catalyst and the
