PO420 code
#1
TECH Apprentice
Thread Starter
PO420 code
So i put some Gumout 4 in 1 fuel system cleaner and less than a week after using it i threw the PO420 code. I know what the code is the left cat could be bad.....I started the car like the 3rd or 4th time since i got the code and it shut off. So do you think it was the gumout that caused the code??