These gases go through your exhaust system, and your catalytic converter reduces harmful emissions through oxidation and reduction reactions. You will need to clean or replace this part if it doesn’t function properly.
You might be able to clear your catalytic converter by getting the part as hot as possible.
Go for a drive on the highway. Try maintaining a speed of at least 55mph for 20 minutes or more if you can. Driving at high speed for a few minutes will cause the catalytic converter to heat up.
Keep in mind that chemical reactions inside the catalyst can cause the component to reach temperatures of 400-600°F, and a clogged component can generate excessive heat. Wait until the temperature of the catalytic converter has dropped to a safe level before inspecting.
You can purchase a catalytic converter cleaner at any auto supply shop.
Check the instructions of the cleaner you buy.
The catalytic converter cleaner will mix with fuel and spread through your engine and exhaust system. You will need to drive until the tank is empty to see a difference in performance.