Hi EmFer's,

I am currently attending my Update 2013 class. Apparently BAR is allowing another CAT test for OBDII vehicles. The Oxygen Storage Capacity test involves driving the fuel mixture rich and depleting the cat of oxygen. The rear O2 goes high, and you then drive the mixture lean, and measure the time the rear O2 signal goes low. The rule of thumb is a measurement of 2 seconds or more indicates a good cat.

Here is a test done on a 2010 Toyota Corolla, and apparently it has a kickasss catalytic converter by BAR standards.

[2010 Toyota Corolla LE, ECM/Inputs/Outputs Scan Data]

I have been taught that an oxygen sensor will not go high unless there are combustibles present in the gas stream. If that is the case why does it take such a long time for the post oxygen sensor to go low after the mixture is driven lean?

Danny from California

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