Hello,
My buddy has a 2015 Automatic transmission Toyota Corolla with just a bit over 200,000 miles on it and two check engine codes. He told me that the other day when coming back from the store, he started it up and it was shaking at idle when it threw the check engine light. He said it would not go faster than 50 MPH (highways near us call for 60-70 MPH). It was still shaking pretty bad when he had to drive it home too. When I was able to check it out with my scan tool, it threw these codes...
P0420 (Catalyst system efficiency below threshold bank 1)
P0301 (Cylinder 1 Misfire detected)
We did some simple fixes first, cleaned the engine air filter, and replaced all four OEM sparkplugs. And after a 10 minute test drive, the car drove fine, no shaking or speed restrictions for us!
Its been about 2 weeks, and the same symptoms have returned. After doing some more research, I am worried it will lead us to a clogged catalytic converter that needs cleaning/replacement. Are there any cleaners that can restore the catalytic converter that my good man Scotty would approve of? He lives in a state where he would need to pass emissions testing.
Have you performed diagnostics to rule out the other possible causes of P420?
https://www.walkerexhaust.com/support/tech-tips/diagnosing-catalytic-converter-p0420-code.html
https://www.obd-codes.com/p0420
@chucktobias Thanks for the links, I checked them out and they are making some sense as to why we would check these steps. I will see the car tomorrow and I will be able to check out the O2 sensor data, but I do not know of a DIY friendly way to check for exhaust leaks. But thanks a ton for the quick response!
Usually you can hear or feel an exhaust leak if you can't find it via visual inspection. You could also do a smoke test if you have access to a smoke machine.
cleaned the engine air filter,
Don't clean, just replace. They're cheap enough.
Are there any cleaners that can restore the catalytic converter that my good man Scotty would approve of?
nope a plugged cat.con. is dead. Absolutely nothing you can do. Replacing is your only option.
here are some images of plugged catalytic converters. There is no miracle product that regrows a catalytic converters.
I would also do it sooner rather than later, because I've heard of the loose pieces getting into the engine and causing damage.
