Cat converter codes range from P0420 through P0438. They’re all directed around
- catalyst efficiency
- catalyst temperatures (warmup and heated).
There are different fault codes depending on
- what bank the bad signal is detected, the condition of the catalyst warmup,
- the temperature(s) of the catalyst(s)
- the efficiency of the catalyst(s)
There is none that specifically tells you it’s your catalytic converter that’s bad. Determining that is up to the technician.
I’ve been arguing for the past few years that, with all the touch-sensitive menus that exist today there SHOULD be available to the car owner a readout the same as that one gets from a code reader, and perhaps even the capability for the car owner to access O2 sensor output scans, and even things like spark pulses. The stuff a scope or analyzer is used for. The capability is clearly there, it’s simply a matter of programming and having a decent display screen. That still would require some interpretation, but it’d be a giant leap for mankind.
But I need to remind myself that the purpose of OBD systems is not to help fix the car. Their purpose is to notify the driver that something that might affect emissions output has gone awry and the car needs to go to a shop for diagnosis. It’s about preventing emissions, not repairing the car.