2011 Highlander P0420 after filling up with diesel

Question

After the wife filled the the 2011 Highlander with Diesel, the car died on the middle of the road. System was flushed and back on the road. A few days later, we stated to get the check engine light along with the Traction control light. We have a P0420. I stated by using a fuel system cleaner. I cleared the code and came back after a few miles of driving.

I then removed and cleaned all four O2 sensors with the same results. I then cleaned the front 3 Fuel injectors as they are easy to get to. No luck! I want to try the rear 3 injector next. I am not sure if I should as they are not as easy to get to. I am not sure if I should try something else instead. Any ideas as of where to go next?

Thanks in advance!

Answer 1

P0420 Catalytic below threshold

The diesel fuel is not easily evaporated, or burned through the exhaust system, Just drive the vehicle especially on the freeway, There been lots of cases where diesel was entered in the fuel tank and had to be drained that set a P0420 , The vehicle was driven and 300 miles later the system was resolved