obd 2 test p1448?

If memory serves me correctly, a P1448 code will be thrown due to the bypass valve and/or a catalytic converter. From my experience, the code usually resulted in a CEL; however, the light may not be on in your car. Just check for any vacuum leaks at the bypass valve as well as the solenoid for the valve. I'd also recommend checking the thermocouple ECU's to ensure theres no moisture in the connections. All quite simple tasks with the removal of the two lateral panels in the engine bay. Clear the code with your tester when finished and see if it ever comes back. Most of the time that code has had no effect whatsover on the performance of the car. Best of luck.