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Old 03-24-2005, 07:36 PM   #1
Scooby Newbie
Member#: 82841
Join Date: Mar 2005
Impreza GC8 Cobb header burning up o2 sensors

I'm on the look out to buy either a Cobb or Borla header (with Stromung exhaust) and have read in other Subaru forums that quite a few people have had to replace burnt out O2 sensors after they've fitted a Cobb header. Has anyone had experince of this? it is something I'll have to constantly check if I do go with Cobb? or is there a remedy to stop this from happening?
Any help is much appreciated, thanks
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Old 03-24-2005, 08:32 PM   #2
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Chapter/Region: SWIC
Location: Tolleson, Arizona
1993 1.8 helL (AWD)
'06 Corolla XRS!


Hm, I think that all aftermarket headers throw an incurable CEL for some reason. (im sure someone will correct me if im wrong) There are various fixes out there for it but none are effective as far as i can tell. Maybe the O2 sensor burning out has something to do with it?
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Old 03-25-2005, 11:53 AM   #3
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Chapter/Region: Tri-State
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2004 impreza rs4sale
'10 Legacy 2.5GT


Mann, that would really suck if my 02 sensor was burnt. I have the Cobb headers(catless) and a MIL Eliminator. Just recently now, my CEL stays on. What's going on?
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Old 03-25-2005, 12:01 PM   #4
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1999 2.5 RS


i've had the borla header for 4 years now, and no cel. can't comment on others. haven't gotten another one yet.
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Old 03-25-2005, 01:49 PM   #5
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Location: Dracut, MA
2015 WRX


yah borla header for my car for more than 1 year with the pony express MIL and no CEL's at all...
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Old 03-25-2005, 03:20 PM   #6
Matt Monson
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Location: Teh Ghetto Garage, CO
99 2.5RS, '85 911
'73 914 and 2012 BRZ


The Cobb headers can burn out your front O2 sensor( A/F) not your rear (lambda). What will happen if this occurs is that the car will bog around 3000rpms because it will dump a bunch of fuel in there and nearly stall. It takes quite a while for it to happen. But if you are worried about the $80 for an O2 sensor, get some other headers and lose 5 or more HP. It is always a balancing act...
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Old 03-25-2005, 06:24 PM   #7
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Location: SFBay
2000 Impreza 2.5RS


Matt, you know what causes this to happen? Thinking if we knew why they died might be able to change something to fix it. Is this a cobb only thing too, or would TWEs do it too? At least how frequent did it got bad- 1 month? 6months? 2 years?
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Old 03-30-2005, 07:20 PM   #8
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Is there a large performance difference between the equal length Cobb headers and the Borla's? I've read that the Borla's have abetter sound to them but would I be sacrificing some performance if I went with them over the Cobb's?
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Old 03-30-2005, 09:45 PM   #9
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the cobb headers provide more torque and hp but are equal length, so the sound is different, no boxer rumble.

i wonder if the rear mechanical cel fix if applied to the front o2 sensor will elongate/stop the 02 sensor from burning out. do you know why this happens so I can try to finda way around it?
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Old 03-30-2005, 10:57 PM   #10
Keith Cournoyer
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MRT's don't burn them out.
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Old 03-31-2005, 12:11 AM   #11
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Chapter/Region: W. Canada
Location: Calgary, AB
1999 2.0RS


I used borlas for two months, and then went to TWEs. I only had the TWEs on for a few days, and I blew my front O2 sensor. I'd say the TWEs were innocent though, and the damage was done when I was still using the borlas. Hard to know for sure, but I don't think a few days would be enough to blow the sensor.
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