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Pontiac Repair/2005 pontiac bonneville GXP


Keep getting cat. Converter codes , had converter replaced twice -aftermarket converters . Do I need an OEM to stop problem

Hi Lee:

Aftermarket converters are an issue with every car/truck. if it's not original equipment the calculations the engine control module makes for calculations as to how much hydrocarbons are burned off have to me spot on or the engine control module will keep tripping a code po420 time and time again. You could have an Oxygen sensor issue that causes this but I doubyt it. that engine has 2 a pre and post converter sensor and the difference between what the 2 of them read tells the ecm to turn the right on. there is hope. depending on where you live some states allow used catalytic converters to be sold. if you live in one of them you could be able to get a used one that will work. BUT it has to be from a another GXP a GT or a regular Grand prix will be different. I'll assume this GXP is supercharged correct? if so you need one out of another car with the exact same engine and if you can find one with even less milage on it then yours that is a bonus! Good luck :-)
Just realized you said Bonneville not Grand prix.. The GXP is the 4.6 north star engine. same idea only different engine and car the system works the same BUT the parts need to be an exact match !  Sorry for my Gaff but the end answer is still the same..  

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Todd Puccio


General auto repair,electrical issues,driveability issues,anti-lock brakes,SIR systems,HVAC,engine performance,Gm specific. I have worked at my current dealership since the 1990 model year anything much older than that I have limited exposure to. I do not have very much transmission experience so those question you may want to ask of another expert. When you send me a question let me know the exact make/model/engine and year for the car or suv you have it makes it easier to answer the questions that way. If your happy with the answer I gave you please feel free to Donate. This is a free service to you and I am not compensated at all by this web site. I have 22 years of experience to share with you and my knowledge wasn't free to me. I had to pay for my education.


Experience in the area: I have been a technician in GM dealerships for over 22 years and I am a ASE master technician. I work at a Buick and GMC truck store Previously I worked at a Pontiac GMC store for 18 years. I Served a a lead technician when dealership was on a team system. I just recently moved to a Buick,Hummer,Saab Store when my franchise was purchased by this dealership. Organizations: ASE master technician


Education/Credentials:High school diploma,2 year vocational school degree 2 year college degree. Associates degree in applied sciences (auto technology)Awards and Honors: GMC master technician

Awards and Honors
Master GMC truck technician Master ASE technician in 9 categories

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