P0420 Catalyst below threshold - Saturn Sky Forums: Saturn Sky Forum
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post #1 of 5 (permalink) Old 12-02-2019, 12:39 AM Thread Starter
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P0420 Catalyst below threshold

So my Sky is at 100,000 and just indicated code P0420 "Catalyst System Efficiency Below Threshold Bank 1". I have not noticed any change in how the engine runs, its not idling rough or sputtering under acceleration; however, I have noticed a significant loss of power when putting the peddle down. It just seems really week, i can barely spin tires anymore. Can a plugged catalytic converter really cause that much loss? Whats the best way to resolve this issue? I was told to try a product called "Cataclean" mixed in with my fuel. Id honestly be fine with just removing the converter all together and leaving the pipe wide open if that would fix it, and I'd imagine it would give me more power than stock without it. I've read the skyforums and looks like its either the converter or the O2 sensor. I have the 2.4 baseline with a 16664 Magnaflow 2.5 quad tip exhaust installed. Any thoughts?
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post #2 of 5 (permalink) Old 12-02-2019, 08:31 AM
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My experience has been that the code indicates a bad sensor if there is no loss of power, and a bad converter if there is.

What you are experiencing does sound like a clogged cat.

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post #3 of 5 (permalink) Old 12-02-2019, 10:21 AM
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What I have done in the past was with a plugged converter, I removed it from the car, rodded it out and replaced it. If you live in a state that has inspections this is the way to go or replace it with new.

"The Sky's The Limit"

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post #4 of 5 (permalink) Old 12-03-2019, 11:17 PM
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2.4 are notorious on every single vehicle they're in to plug around the 90k-110k, some even sooner. I've seen it on Terrains, Skys, Solstice, G6, Malibus, Impalas....all of them. I'm guessing with your mileage it's plugged. An O2 sensor though is cheap...about $40...a cat on the other hand....
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post #5 of 5 (permalink) Old 12-06-2019, 01:59 AM
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You need a new catalytic converter. Any muffler shop can handle it. For me the total cost was 375. 325 + 50 labor.

Drop by. Have them order a catalytic for a Pontiac Solstice - and a few days later come in for the install.
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