I have a 2001 Chevrolet Prizm with check engine light showing PO420 and PO446 codes, what could be the problem?
You’re probably just going to need a mechanic at the very least for diagnostic purposes. Here are some helpful web pages:
http://www.obd-codes.com/p0420 (possible catalytic converter failure, but could be several other things)
http://www.obd-codes.com/p0446 (probably vent valve or valve wiring problem)