I have a 2019 Hyundai Tucson with a 2.0L GDI (no turbo)
About 6 months ago, after a road trip of about 700 miles, the P0420 code came up, car was at 55k miles.
I thought it was a fluke and cleared the code. 6 months and 3000 miles later, the code came back. This time, I did more digging and looked at the data from the vehicle. Catalyst monitor bank 1 running below the minimum value. This value seems to fluctuate and sometimes goes back to the normal range.
The car drives smoothly with the engine temp staying in the normal range (around 200 F). No issues with acceleration and no noises coming from engine/exhaust system.
I do notice that the car does burn some oil, I had to add about 3/4 of a quart after driving 3000 miles.
I keep up with oil changes every 5000 miles and put gas from top-tier dispensing stations only (mainly Costco).
Could the cat really be going bad at this low mileage? What other issues could be going on?
It should not but since your car burns oil, it will decrease the life of the your cat. I would call the Hyundai dealer and have them fix it under warranty. It should be covered by law considering age and mileage of your car.
