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2004 GTP Code P0420

G

Gohan77

New member
Hi everyone. New to the forum but not to Grand Prix's. This is my third one and so far my favorite. However I got a code today of P0420 twice. I have a custom exhaust (SLP Loudmouth exhaust 2.5") but i believe the cat was left there. Is it the o2 sensors or the cat itself? Hopefully it's the sensors, but I can live with getting a new cat; i guess it could be a lot worse than that. Ideas?
 


Gohan77 said:
Hi everyone. New to the forum but not to Grand Prix's. This is my third one and so far my favorite. However I got a code today of P0420 twice. I have a custom exhaust (SLP Loudmouth exhaust 2.5") but i believe the cat was left there. Is it the o2 sensors or the cat itself? Hopefully it's the sensors, but I can live with getting a new cat; i guess it could be a lot worse than that. Ideas?
Click to expand...

Google spark plug fouler trick..do that and see if the code continues to appear.
 
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