I have the service engine soon light on. I went to Autozone and had the code read it ame back with P0420 and P0446. I have had the P0420 code beofre and changed all the o2 sensors. A week later the code came back. I put a new fuel cap on has the one I had the rubber seals was cracking. I have cleaned the EGR. I dont think that it is the Cat as I don't have any problems idling or accelerating. I replaced the Cap, plugs and wires.Not sure what else to check for the P0420 code.

For the P0446 code I am not sure where to start looking for the problem. I would apprecaite any help.


I have a 2001 Chevy Blazer 4.3L with 135,000 miles. 2dr/2WD.

 

P0420 - Catalyst System Efficiency Below Threshold (Bank 1)
P0446 - Evaporative Emission Control System Vent Control Circuit

P0420 typically results from a catalytic converter that is not functioning properly.

P0446 is telling you that there is a problem with the vent solenoid circuit. The vent solenoid is located under the truck near the back of the fuel tank. On a 2dr, it will be behind a little shield.