Hi All

I got a code P0420 the other day this is the second time I have had this code. Before it went from p0420 to p01133. I replaced the precat O2 sensor and have a new extension harness from ZZP. Now Im back to having a P0420 code. What can I do to fix this?
Thanks Keith

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2001 SSEi Bumbles
Angel Eyes ~ Cleared Corners ~ Tinted Tails ~ Intense FWI ~ 20% Tint ~ 180 Drilled T-Stat ~ GXP Brake & Suspension Upgrade ~ Alternator Rewire ~ Intense Shift Kit ~ Headers ~ Tr 6's

1992 Bonneville SSEi (Sold)
Fan over ride~NGK Tr 55's~180 Drilled t-stat~Clear Corners~Angel Eyes~Tinted Tails~Magnaflow Cat

What downpipe/Cat are you running?
P0420 is a low efficentcy cat code.. caused by a bad cat or a high flow cat. you have access to a tuner or know anyone with DHP? you can tune it out or buy a spoof to disable the 2nd cat.. i have not tried it on 3800 but i know a lot of people that have had great luck with the CEL fix that screws in to the bung and pulls the O2 sensor out of the flow (some have a little cat metterial in them, do a google search and you will find them)

S

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Shane "RedZMonte"
2004 Z16 Z06: Virgin
2000 SSEi: Kenwood DDX512, 3.25" MPS, ZZP DP, PLog, Puck Mount, NGK TR7's, DHP Tuned
1995 Monte Z34: T04e "60" turbo, 42.5# injectors, Borla Catback, OBDII swap, DHP Tuned, Much more...

What kind of tool are you using to put the sensor on? Reason I asked is because I had trouble out of bank 1 sensor one 1, 2 new Delco's went bad within 300 miles and noticed that it was the O2 sensor socket that was damaging the O2 sensor, I started using a crowsfoot socket and haven't had any problems so far.

Keith, if you can't get a tuner to turn off the code, you can get an emulator from ZZP. It will mock an O2 sensor functioning with a stock cat, making your issue go away.

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Will
88 Cutlass Ciera Brougham International | 120k mi | White w/ Dk Claret Int. | Roller to be S2 L67/4T65E-HD | 1 of ~5100 3.8 FE3 Int'l series
91 Riviera | S2 L67 Swap/4T60E | 127K mi | Antelope Met. w/ Tan Int. | Saved From Death By Crusher
92 Bonneville SSE | L67/4T60E | 77K mi | Med Slate Grey w/ Two-Tone Grey Int. | Low Miles Time Capsule
92 Lumina Z34 | LQ1/4T60E | 177k mi | Torch Red w/Grey Int. | Rusty In Odd Spots
99 Tahoe LT | L31/4L65E | 276k mi | Spiral Grey Metallic w/Grey Int. | Truck for Truck Things and Portable Concert Hall
03 Park Avenue Ultra | 212K mi | White Diamond Met. w/ Shale Int. | Southern Time Capsule
05 Acura RL | 155K mi | Carbon Grey Pearl w/Ebony Int. | The Super-Hooptie Daily

Im running pacesetter headers and cat is deleted. I use a 02 socket to install them I check the wires after the install and they normal. Pretty much this code is just for a O2 sensor? I dont have access or know anyone close by that would be able to tune it out and fron what zzp and intense offers its the rear o2 code they delete out not the front.

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2001 SSEi Bumbles
Angel Eyes ~ Cleared Corners ~ Tinted Tails ~ Intense FWI ~ 20% Tint ~ 180 Drilled T-Stat ~ GXP Brake & Suspension Upgrade ~ Alternator Rewire ~ Intense Shift Kit ~ Headers ~ Tr 6's

1992 Bonneville SSEi (Sold)
Fan over ride~NGK Tr 55's~180 Drilled t-stat~Clear Corners~Angel Eyes~Tinted Tails~Magnaflow Cat