PontiacBonnevilleClub.com

2001 SSEi - 84,000 miles

74000 miles Replaced rear O2 sensor
84000 - Replaced Catalytic Converter
84000 - replaced upper O2 sensor

only use sunoco 93 gas(maybe a 92 here and there)
(occasionally use a Lucas bottle/ maybe 1x a year, car ave. 5000mi per year)

P00420 would go off maybe every 1500 miles or so
now, every 120 miles now she puts out the P0420 code

symptoms (only because im really looking due to light)
when under load (climbing a hill) and if RPMs are around 1200 she sounds like shes struggling, like i have to give it a lot of gas, soon as i press on gas she goes
gas mileage is about 15.8 in town

will update if i see more

some info for you in between code resets

http://www.easterncatalytic.com/educati ... 420-codes/

https://www.obd-codes.com/p0420

What cat did you put in?

I don't know, I paid to have someone do it and they ordered the part.
I took it to my regular mechanic to have things assessed.
He said looks like an aftermarket "performance" cat was used. The code is most likely due to the cat.
He suggested eiter remove this one and put on a OEM replacement, or buy a tuner and ignore the P0420 code. (as well as enjoy other benefits of tuner)

He said the current cat is not harming the car.

feedback?

what?, the guy who installed it doesnt know what he installed - call him and get the order reciept/invoice. you need a 50 state legal cat or the cali/Canadian one to avoid issues

no I dont believe that any harm will be done , but, you're not going to pass emissions with the code

If necessary, you could go the route of an emulator.
https://zzperformance.com/3800/o2-emulator

Since it struggles up hills, it makes me think you have some kind of ignition system issue. Is there any other indication of troubles? Does it feel good when you're WOT?

You need a name brand Heavy Metal catalysis, he probably put in a cheap Chinese piece of junk and charged you for a good one.

I recommend the Magnaflow 99306HM (around $100 online), I install them on all my project cars, never had them throw a code.

Thanks for the recommendation.

nos4blood70 wrote:Since it struggles up hills, it makes me think you have some kind of ignition system issue. Is there any other indication of troubles? Does it feel good when you're WOT?

I have had ignition problems cause a P0420 before.
With your mileage, if your plug wires are original you may want to consider changing them and also check plug gaps.

at 60000miles i had new plugs wires done