That’s an O2 sensor 1/1 fault. Exactly what sensor did you replace? NOX, temp, or O2, and which one (from closest to furthest from engine)?Ok, cool. I have a code P0030 and after looking it up I ordered a new NOx temp sensor number one position and replaced it. I’ve cleared the codes with two different devices but the code remains and now it has my truck in limp mode 5 mph. Any suggestions.