[Rob454]

I got 2 codes on my truck tonight. 0420 0431
One says catalitic below threshold left side the other says main catalitic efficiency below threshold right side. I dont drive the car much anymore. it sat for a week at a time and got driven very little in the past month
Thanx for any replies
Rob

 

[SinCity R/T]

Your OEM Catalytic Converter may be going bad, or the O2 sensors checking the catalytic converter may be bad. Catalytic converters have a huge warranty separate from the rest of the vehicle, IIRC 8 years or so - if you're within that threshhold check with your dealership for a checkup.