ECU Testing frequency

[babur]

Hi there,

I have a 2001 Boxster w/ 82K miles. I had a P0430 code (cats). Ignored for a week or so but then I had problems with the MAF so I had to change it along with the spark plugs, air filter, etc and reset the code.
Since then, I drove the car 250 miles or so... and still no CEL!:-)))

My question is: How often does the ECU retests the engine? I would assume that it is an ongoing process and if truly I had a cat converter problem, the CEL should have been back by now, right? Am I off? Or is it simply a matter of time?

Thanks

Bob