The other day my car kept stalling. Then it ran fine for a day or two, then the PO420 light came on, and a day later started having the stalling problem again; however, the car could started back up shortly after stalling. The next day when the car stall it could not be started back up. What could be causing the P0420, and could that cause the car to stall and not be started back up? Any comments or suggestions would be great! Thanks!

 

clogged/bad catalytic converter maybe?

 

Thanks for the reply. Is there a reason the CEL didn't come on until a couple of days after the car had the stalling problems? Could the CEL, which I assume is related to the CAT or O2 sensor, have come on as a result of a different problem "upstream" on the car thus giving bad readings to the "downstream" sensors?