What engine do you have?
---------- Post added at 08:31 AM ---------- Previous post was at 07:41 AM ----------
To answer your question... I would get the CARB certified catalytic converter no matter where I lived. Specifically, I'd get the original equipment part. The reason being, the OEM catalytic converters are 3-way catalysts that reduce hydrocarbons, carbon monoxide, and oxides of nitrogen. I would want the converter that has the catalysts to control all three types of pollution.
Every time I admire a 1960's muscle car, such as this beautiful 1961 Corvette convertible I was gawking at yesterday, I am reminded how horrible out air would be if emissions equipment were not required. When that 61 Vette pulled away from the stop light, I about died. Not from how fast it took off, but from how sick the exhaust, that wasn't even visible, made my biological breathing apparatus feel. Our car population has expanded exponentially since the 60s. Imagine if all cars on the road gassed us out like that.
That code you pulled indicated that your catalytic converter's oxygen storage capacity has degraded to less than the calibrated threshold for it to continue to convert deadly and toxic carbon monoxide emissions into greenhouse gas producing carbon dioxide emissions.
The fix flow chart (that GM recommends) is exactly as I stated above. Check the connectors, pigtails, and wiring harnesses to the sensors. Make sure they are not damaged or contacting the exhaust. Do this before shopping for converters. If Alldata granted you access to the full compendium of service data for this concern, that is what you would find written.
It makes sense when you think about. How would the PCM know the condition of the catalyst without getting an electrical signal from somewhere? The foot bone is connected to the hip bone by the leg bone, and the leg bone in this case is the wiring and sencors. To figure out what is going on with the Catalytic converter, the PCM reads a bank of heated oxygen sensors.
One of these heated oxygen sensors is downstream of the 3 way catalyst... the rear sensor. Another heated oxygen sensor is upstream of the catalyst... the front sensor. The PCM measures the response time it takes for the rear heated oxygen sensor to cross a reference rich to lean threshold, minus the response time it takes for the front heated oxygen sensor to do the same thing. The difference between the front time and the rear time indicates the oxygen storage capacity of the catalyst. The P0420 code sets if the time exceeds the predetermined threshold.
The electrical signal range is from less than 300mv to more than 600mv, and vice a versa for lean to rich ratios. So with signal voltages in the millivolts, you want to make sure the wiring is good before throwing parts at it.
The historical code will self clear if no failures are reported by this or any other emissions related diagnostic trouble codes after 40 consecutive full warm up cycles. The check engine light on the dashboard will turn off after only 3 consecutive ignition cycles that the diagnostic runs and does not fail. The current code will clear whenever the diagnostic runs and passes.
If your wiring is all good, then a new catalytic converter is recommended.
Good luck!
(these smiley heads are the tech and the service manager arguing about "Did you replace the sensor first before just replacing the sensor?") LOL!
