Do I need to replace the catalytic converter

Question

I have a 2017 Toyota Camry with 170,000 miles. I’m getting a P0420 code. I already replaced both the upstream and downstream oxygen sensors with OEM parts, but the code still returns. Do I need to replace the catalytic converter? Is it okay to use a catalytic converter purchased from Amazon? after market

Glen_stet · Accepted Answer

Unless you have a exhaust leak, yes. See https://www.autocodes.com/p0420_toyota.html

I personally would not trust the "Brand X" $150 cats on Amazon, but if you were going to go with an aftermarket, non-original equipment cat from a known brand, such as Walker, they are much cheaper on Amazon than from your local auto parts store. However, I'd take the safe route and go with Toyota OEM. Note that shopping around on the internet for OEM parts can give you much better prices than at dealerships or parts stores.

Chuck Tobias · Answer

Check carefully for the other possible issues which can trigger that code. Proper diagnosis is preferable to throwing parts at a problem.

https://www.walkerexhaust.com/support/tech-tips/diagnosing-catalytic-converter-p0420-code.html

https://www.carparts.com/blog/p0420-code-catalyst-system-efficiency-below-threshold-bank-1-2-2/

If your converter is actually bad - catalytic converters don't normally just "go bad" for no reason. You may have an underlying issue with your engine. (Oil burning or running too rich would be the main things that would poison a converter.) Unless any underlying issues are fixed a replacement converter may not last long.

thdesha · Answer

If the car runs okay I would ignore it...a 420 can be caused by all kinds of things that can be hard to figure out...the car will run another 50,000 miles most likely...