P0420 Check Engine Light

Discussion in 'Hyundai Accent' started by Crashmaster, Dec 1, 2023.

  1. Crashmaster


    Feb 28, 2023
    Likes Received:
    I have a 2020 Accent. The check engine light came on with a P0420 (Catalyst System Efficiency Below Threshold Bank 1). Yep, seen that one before on other vehicles and don’t really want to spend $1000 to $1500 for a new converter. I decided to try the Dura Lube Catalytic Cleaner in the gas tank. Made no difference. Tried again on the next tank of gas. Still no difference. Then tried installing the spark plug fouler on the oxygen sensor. Again, made no difference. Tried the Dura Lube Cleaner again. Still no difference.

    I have not done the below yet, but plan to: Add about a half-gallon of Lacquer Thinner to the gas tank and then pull the converter and soak it in Dawn dish washing detergent overnight to clean it.

    This is my first Accent and wanted to post this to see if anyone has any other ideas besides replacing the Catalytic Converter? Any thoughts with the above?
    Crashmaster, Dec 1, 2023
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