I have a 2016 Equinox with a 4.2L. There have been two aftermarket converters insalled but the p0420 code keeps coming back. I'm being told the only to resolve this is to install an OEM converter from Chevy and not use aftermarket. Does anyone know if this correct? I find it hard to believe there is not a compatible aftermarket converter what will correct my issue without spending $1400 for an OEM converter. Any suggestions would be greatly appreciated.
1. Replacing the oxygen sensors, before they throw a code can save a catalyitc converter. I suggest you change both out. One is behind or beside the engine, the other near the catalyic converter. The one by the engine is easy to get to and replace. The other is DIY too, once you get under the car.
2. Caked up injection valves can release chunks of carbon build up that can burn a hole in the catalytic converter. The Direct Injection valves don't get cleaned by the stuff you pour in your gas tank. Still use that stuff, but it doesn't reach the top of the valves. You have to use a product like CDC Direct Injection Valve Cleaner. Let it soak over an hour and you may have to repeat after 1,000 miles. CDC says it continues to work for 1,000 miles so to do it more frequent is a waste.
3. See the last suggestion on this video. It might fix your issue.
https://www.google.com/search?q=p0420&sourceid=chrome&ie=UTF-8#kpvalbx=_L1A9Zd3wL8OHqtsPteKVyAg_28
4. Rock Auto does have really good prices. Walker is supposed to be the best out there for catalytic converters.
I always use OEM when possible, but there's times you can go with a good brand and be okay. Sorry this happened to you guys.
Another tip: Replace all your sensors at the 90k mark or at least before the 105k miles mark. They go out slowly losing efficiency along the way and can cause other expensive issues before you even realize the sensor needs replaced or throws a code. MAF, MAP, Coolant temperature, Crankshaft, O2, to name a few. The O2 sensor by the catalytic converter fails first and most often. It's usually called bank 2.
Shop around, most of the sensors are not expensive and easy to replace yourself if you have a 10mm socket, pliers and a screwdriver.
Don't forget, NAPA (in store only) has 30% off everything during the 1st hour of being open on the 2nd Saturday of the month. Not all stores honor this, so call first. In store only. The rest of the day and 2nd Sunday it's 20% off. Pretty sweet deal!!
Btw - I have found NAPA brand stuff to be pretty darn good quality.
I've also had to resort to Ebay for OEM parts and those worked out. Usually Rock Auto has the best prices and they get stuff to you pretty fast.
