2003 Pontiac Grand Prix GTP
20

Asked by David J Apr 04, 2019 at 07:23 AM about the 2003 Pontiac Grand Prix GTP

Question type: Maintenance & Repair

So was driving home from work the other day and
went to pass a slow moving vehicle... when I
kicked to passing gear the car started to die out
almost like a misfire and the check engine light
came on and started flashing... so I got home put
the code reader on it and got P0420, emission
control problem, catalytic converter plugged up I'm
pretty sure... my question is can I just cut it off? I
have no emission testing where I live so I could
and just straight pipe it to the resinator but would
that interrupt my back pressure? I've heard engines
can blow without proper back pressure so I want to
make sure. I'm gonna change my spark plugs and
check my fuel delivery too but I'm pretty sure it's
that catalytic.
TIA.

3 Answers
2,600

Sirkut_Interrupted answered 5 years ago

P0420 isnt a plugged converter.. its a inefficiency code meaning its storing oxygen like it should when the computer monitors it.. the symptoms your descirbing are gonna be from a fuel delivery issue. low fuel pressure under load or a dirty mass air flow sensor. Unplug the maf and see if the situation improves

Mark helpful
2,600

Sirkut_Interrupted answered 5 years ago

If you have to find some way to tape a fuel pressure gauge to your windshield and drive it up the road real hard and make sure pressure dont drop out ive had to do that before too

Mark helpful

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