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Need Help! Installed new cat and threw a check engine

 
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Old 09-11-2007, 11:31 AM
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Need Help! Installed new cat and threw a check engine

Hi everyone. I need a little help. I just installed a new OBX high flow cat on the car and it throwed a checked engine light. I asked the seller before hand if it would, and obviously he lied. What can I do? Should I just go find a used stock cat or is there a by pass harness I can purchase to elimiate the check engine light???
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Old 09-11-2007, 02:00 PM
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did you remember to hook both o2 sensors back up??
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But you need that scoop on the hood. Is it true that they're big enough to fit your lunch box and all your camera gear in it?
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Old 09-11-2007, 02:24 PM
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Yes, both o2 sensors are hooked up. I guess I have to go pull the code and see what it is and then go from there. Thanks
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Old 09-11-2007, 08:35 PM
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cat problems

Is it a high flow cat or "test pipe"? A test pipe has no matrix and will always throw a code. I have a Magnaflow cat on my 98 base and it always has the check light on for "catalyst under threshold" because high flow cats do not meet factory specs. As long as you keep your stock ECU it will throw that code. I have a OBD2 code reader/analyser and make sure that my check engine light has no other codes other than "catalyst under threshold" code and then ignore the check engine light. If it bothers you and you do not want to monitor the codes as I do, then either change back to a stock cat or get an expensive aftermarket ECU that will accept the high flow cat. I do not recomend buying a used cat as they are like mufflers, they wear out and you have no idea how long a used one will work.
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Old 09-11-2007, 08:54 PM
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There's a couple things to check before blaming the cat. If you have access to a scan tool see if it's a code for HO2S2B1 (Sensor 2, Bank 1. The rear O2 sensor) or if it's a catalyst efficiency code. Also check for leaks in the exhaust before the cat.

As far as I'm concerned, OBX stuff is worthless. I bought a set of their headers for my '99 Sentra SE-R and they were just dispicable. I can't even imagine what kind of cheap materials they use in their cats. The only company who trully knows how to make good hi-perf cats is Random Technology. I went through the trouble of having them custom build me a cat for my old '99 Sentra and it was worth every penny and hour spent.

What satwilson said about high flow cats not meeting factory specs is not completely true. I've seen Random cats do better on a five gas analyzer than some OEM cats. But ya, I can almost guarentee that an OBX would throw a P0420 or similar.
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Old 09-11-2007, 10:51 PM
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Thanks guys. I have to go pull the code tomorrow.
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Old 09-09-2008, 02:06 PM
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Re: Need Help! Installed new cat and threw a check engine

I have a random tech hi flow in my car and it's throwing the p0420 code, I heard from a buddy that if you put a washer or two on your post cat sensor to pull it out a little and sort of de-sensitize it, that can fix the problem has anyone tried it? I'm gonna give it a shot this thursday
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Old 09-09-2008, 02:11 PM
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Re: Need Help! Installed new cat and threw a check engine

With a stock ECU and no O2 sensors will your car run rich?
I have a test pipe and DC headers not 1 O2 sensor and its running rich.
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Old 09-09-2008, 03:43 PM
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Re: Need Help! Installed new cat and threw a check engine

might be the test pipe. i have neither O2 hooked up, and the AFR's barely ever go above 15.
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1995 Honda Prelude SE Turbo; 250whp, 275wtq @ 10psi Soldddd!!!

2000 Acura TL; DD
2005 Stage2.5+ Subaru WRB STi : RzKar!
Ivey Tuned - Advan - Cobb - Rallispec - CP - Perrin - ACT - KillerB - Carillo - TurboXS - Defi - Innovate - Walbro - DeatschWerks - Feal - H&R - Alpine - Infiniti - Curt

2001 Kawasaki STX1100 D.I. - Sold!
2007 Sea-Doo RXT 215; ET 127 +3 S/C impeller, DIY 3" intake, DIY resonator delete/free flow exhaust, DIY oil catch can, Rule 500gph bilge pump


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Originally Posted by Brash View Post
But you need that scoop on the hood. Is it true that they're big enough to fit your lunch box and all your camera gear in it?
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