does anyone know what size spark plug anti fouler i need to get p0420 to shutup also do you really have to drill it out before you can put it on thanks

 

try googling around. i just ran across a article about this like a month ago but no idea where it was. if you do it post up the results, i kinda want to know if it works

 

ha this prob. wont help but, my old cavalier would not stop throwing the p420 code no matter what. I thought it was to do with the hi flow cat but now that i think back one of the plugs use to get some oil on it and this would have bean a good idea...

 

i know its been awhile but i finally got around to trying this out i used a set of 18mm spark plug non foulers and i drilled one of them out far enough to fit the post cat o2 sensor inside then i put the other one on the end put the whole thing back in the exhaust cleared the the code with a scanner and guess what NO MORE LIGHT! its been off for about 100 miles now best $5 fix ever