Check engine code
 

2001 Boxster S, I got the following trouble code with my Foxwell scanner: P0430/$11 “ Catalyst system efficiency below threshold bank 2”. I understand that this is an O2 sensor, but which one.? Thanks

It may not be the O2 sensor, that code is specific to the performance of the cat.

Like JFP mentioned, the code is most likely related to the cat performance.

Bank 2 is on driver side at the Boxster (left hand side driven cars). This means that it would be the later O2 sensor on bank 2 that sniffs the cat problem.

So then... it could be the sensor and it's not sniffing properly? Or, as JFP said... cat problem. One or the other? Thanks. :cheers:

Easy enough to find out, check the sensor electrically, if it is working, it ain’t the sensor.

The front O2 sensor only reports what it is receiving and the rear one likewise reports how well the cat did its job. The problem may be upstream. The air mass may not be sensed correctly, the throttle body may not be reacting promptly, the injectors may not be operating correctly and thus the air/fuel mix is not correct, doesn't get burned and dumps too much unburned stuff into the cat for the cat to absorb.

So lets start...it is an '01 base or S? How many miles. Otherwise running OK? What tool did you use to pull the codes? Any others showing? Any recent work anywhere in the engine bay? Is the air pump that adds O2 just after startup working? Any hose leaks?