Check engine light p0420 code just replaced Catalytic converter two months ago.?
So I was driving and out of nowhere my check engine light came on the code P0420 came on When I scanned it I’m confuse weather is an O2 sensor or something else that may be causing the code I’m wondering if it’s the catalytic converter breaking into t when I scanned it I’m confuse weather is an O2 sensor or something else that may be causing the code I’m wondering if it’s the catalytic converter breaking into car. I clear the check engine light and it has come on in the week does anybody know about this
Dan2019-02-27T17:27:26Z
Not the O2, cat was likely cheap aftermarket. The new cat must have a label that says it's approved for use in California even if you live elsewhere.
The most common cause of P0420 codes, in my experience, is an exhaust leak ahead of the converter. A muffler shop can check that for you at a reasonable price and fix it if necessary.
Another common contributor (never a flat-out cause on a new converter, in my experience) is dirty fuel injectors. If you use whatever gas is cheapest it can be a real issue.
If your car is a VW you can't use after market catalytic converters. You must use a factory converter. The only after market converters I use a re Walker brand converters. They have a 75% success rate for not triggering the P0420 code again. It's not 02 sensors. The fact the P0420 code is setting means the 02 sensors are working.
Replace the rear O2 sensor with a factory (OEM) sensor. Clear the codes. No fix, time to see a mechanic with a scanner. If you installed an aftermarket converter, that could be your problem.