I bought a 2004 GMC Yukon Denali with 2 codes. P0420 and P0430. Catalytic converter prices are at an all time high. I decided to try and clean the catalytic converters with lacquer thinner, after seeing a video by Scotty Kilmer.
Scotty Kilmer claims that a gallon of lacquer thinner added to 9-10 gallons of fresh gas, and then driven at 2,000 rpms till the tank is empty has a good chance of cleaning lightly clogged or cats that are not functioning fully. I don't understand the chemistry behind it, but there are several people who have tried it with success. To replace the cats on my GMC would have been more than $1,200.
During my repair of the Yukon, TOPDON offered to send me a code scanner to help me diagnose the issues I was having. They offered a discount code for my viewers as well. If want to try the code scanner that I use in this video here.
https://amzn.to/3wB8F2k