CEL after adding headers
Thread Starter
Drifting
Joined: Mar 2005
Posts: 1,424
Likes: 21
From: Placitas New Mexico
CEL after adding headers
I have read that after headers are installed you usually get a CEL. Can this be shut off without a tune? I intend on getting cats also.
The reason I ask is my local dealer said he would honor my warranty if I installed headers or an intake as long as they don't cause the problem I want fixed under warranty. I don't want a CEL all the time. I don't know if they'd be okay with the tune. I was going to take one step at a time
The reason I ask is my local dealer said he would honor my warranty if I installed headers or an intake as long as they don't cause the problem I want fixed under warranty. I don't want a CEL all the time. I don't know if they'd be okay with the tune. I was going to take one step at a time
Safety Car
Joined: Sep 2007
Posts: 3,502
Likes: 82
It may take a few days but you almost certainly will get a CEL for the rear 02 sensors. Their job is to monitor the health of the catalytic converters and the cats that come with long tube headers are too far downstream to keep the rear o2 sensors happy.
Safety Car
Joined: Sep 2007
Posts: 3,502
Likes: 82
NO...what makes the difference is that the parameters the rear o2 sensors are expecting are not met by the relocation of the cats so far away from their OEM position (take much longer to heat up) and the fact that aftermarket cats are not as efficient at scrubbing the exhaust.
Most tuners will simply tune out the error codes for the rear o2's that set the CEL. The conditions are still met for the CEL but the computer is told to ignore those conditions.
I run my 2009 without rear o2 sensors (no reason for them to be there) and I have all reporting for the rear o2s tuned out. No CEL here.
My rear o2 sensors...
Most tuners will simply tune out the error codes for the rear o2's that set the CEL. The conditions are still met for the CEL but the computer is told to ignore those conditions.
I run my 2009 without rear o2 sensors (no reason for them to be there) and I have all reporting for the rear o2s tuned out. No CEL here.
My rear o2 sensors...
Last edited by Motorhead-47; May 21, 2010 at 10:06 PM.
Safety Car
Joined: Jun 1999
Posts: 3,570
Likes: 3
From: Austin, Singapore, Kuala Lumpur, Houston, Dallas, Hong Kong, Elgin, etc.. Texas
I have read that after headers are installed you usually get a CEL. Can this be shut off without a tune? I intend on getting cats also.
The reason I ask is my local dealer said he would honor my warranty if I installed headers or an intake as long as they don't cause the problem I want fixed under warranty. I don't want a CEL all the time. I don't know if they'd be okay with the tune. I was going to take one step at a time
The reason I ask is my local dealer said he would honor my warranty if I installed headers or an intake as long as they don't cause the problem I want fixed under warranty. I don't want a CEL all the time. I don't know if they'd be okay with the tune. I was going to take one step at a time
Don't assume the CEL is related to the O2 sensor. There is a good chance but you should have the code read to confirm. But it also could be related to something completely different.
Do you have the front 02 sensors hooked up? What about the rears? The rear 02 sensors only function is to verify the cats are working.
Last edited by Mez; May 21, 2010 at 10:20 PM.
Safety Car
Joined: Sep 2007
Posts: 4,359
Likes: 6
From: Los Alamitos California
St. Jude Donor '09
NO...what makes the difference is that the parameters the rear o2 sensors are expecting are not met by the relocation of the cats so far away from their OEM position (take much longer to heat up) and the fact that aftermarket cats are not as efficient at scrubbing the exhaust.
Most tuners will simply tune out the error codes for the rear o2's that set the CEL. The conditions are still met for the CEL but the computer is told to ignore those conditions.
I run my 2009 without rear o2 sensors (no reason for them to be there) and I have all reporting for the rear o2s tuned out. No CEL here.
My rear o2 sensors...
Most tuners will simply tune out the error codes for the rear o2's that set the CEL. The conditions are still met for the CEL but the computer is told to ignore those conditions.
I run my 2009 without rear o2 sensors (no reason for them to be there) and I have all reporting for the rear o2s tuned out. No CEL here.
My rear o2 sensors...
San
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Tech Contributor
Joined: Mar 2003
Posts: 12,094
Likes: 197
From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
Anything you change to the engine that affects airflow requires a tune, no excpetions. Deleting cats and rear O2's requires a tune. Brand is irrelevant. This topic pops up from time to time and so does my explanation because internet myths need to be kept in check. Your engine maintains stoic a/f ratio within a -14/+24% range and when you go outside that range you get a CEL. Anyone and everyone who changes an aircleaner or exhaust parts changes the airflow and thus changes the part throttle fueling. If a person says he installed headers and didnt get a CEL, that doesnt mean his car is running correctly, it means he can be at +23% and way off on WOT fueling so its far from optimum even without a CEL.
So the reason you have the CEL is because it is running lean at part throttle and as a result of that, you are running grossly rich at WOT. Long term it damages the car to not have the fueling right.
The tune will violate the warranty. If thats important to an owner, dont mod.
So the reason you have the CEL is because it is running lean at part throttle and as a result of that, you are running grossly rich at WOT. Long term it damages the car to not have the fueling right.
The tune will violate the warranty. If thats important to an owner, dont mod.
Drifting
Joined: Jul 2006
Posts: 1,840
Likes: 7
From: no. jersey Photo by Stro
St. Jude Donor '08
Anything you change to the engine that affects airflow requires a tune, no excpetions. Deleting cats and rear O2's requires a tune. Brand is irrelevant. This topic pops up from time to time and so does my explanation because internet myths need to be kept in check. Your engine maintains stoic a/f ratio within a -14/+24% range and when you go outside that range you get a CEL. Anyone and everyone who changes an aircleaner or exhaust parts changes the airflow and thus changes the part throttle fueling. If a person says he installed headers and didnt get a CEL, that doesnt mean his car is running correctly, it means he can be at +23% and way off on WOT fueling so its far from optimum even without a CEL.
So the reason you have the CEL is because it is running lean at part throttle and as a result of that, you are running grossly rich at WOT. Long term it damages the car to not have the fueling right.
The tune will violate the warranty. If thats important to an owner, dont mod.
So the reason you have the CEL is because it is running lean at part throttle and as a result of that, you are running grossly rich at WOT. Long term it damages the car to not have the fueling right.
The tune will violate the warranty. If thats important to an owner, dont mod.
I just put Kooks LT w/HF cats and xpipe (all ceramic)and verry happy.
What DAMAGES do you mean so I can do something about it bfore it happens. I also like my Flowmasters to. Vararam is next, say a month or so.
TIA
David
Team Owner
Joined: Aug 2003
Posts: 38,314
Likes: 35
A lot harder to find now than they used to be, since one of the companies which was a big player in the 02 sim business, got hit pretty hard by the EPA.
I can remember when these were very easily found from a number of the catalogue aftermarket car performance companies.
http://www.epa.gov/compliance/resour...aa/casper.html
http://www.fquick.com/blog/Caspers_E...by_the_EPA/467
I can remember when these were very easily found from a number of the catalogue aftermarket car performance companies.
http://www.epa.gov/compliance/resour...aa/casper.html
http://www.fquick.com/blog/Caspers_E...by_the_EPA/467
Drifting
Joined: Dec 2009
Posts: 1,320
Likes: 58
From: Benicia CA
A lot harder to find now than they used to be, since one of the companies which was a big player in the 02 sim business, got hit pretty hard by the EPA.
I can remember when these were very easily found from a number of the catalogue aftermarket car performance companies.
http://www.epa.gov/compliance/resour...aa/casper.html
http://www.fquick.com/blog/Caspers_E...by_the_EPA/467
I can remember when these were very easily found from a number of the catalogue aftermarket car performance companies.
http://www.epa.gov/compliance/resour...aa/casper.html
http://www.fquick.com/blog/Caspers_E...by_the_EPA/467
Burning Brakes
Joined: Dec 2007
Posts: 1,015
Likes: 1
From: Maryland
St. Jude Donor '08
I think that the OP's main concern is protecting the integrity of his powertrain warranty.
The OP been told by his service department in no uncertain terms that if he "tunes" the vehicle, his warranty is toast.
I believe that the OP lacks an understanding of what the definition of a "tune" is, at least according to GM.
With that said; a "tune" would be defined as changing any of the original factory GM PCM or TCM calibrations that the vehicle left the factory with.
That of course would include simply shutting of the rear O2 sensors simply to defeat the inevitable CEL that would ultimately occur because the AFR MAP tables were not recalibrated to recognize the new high flow intake and/or exhaust.
So the bottom line is that if change any of the original ECU calibrations your 5yr/100,000 mile powertrain warranty is voided.
The OP been told by his service department in no uncertain terms that if he "tunes" the vehicle, his warranty is toast.
I believe that the OP lacks an understanding of what the definition of a "tune" is, at least according to GM.
With that said; a "tune" would be defined as changing any of the original factory GM PCM or TCM calibrations that the vehicle left the factory with.
That of course would include simply shutting of the rear O2 sensors simply to defeat the inevitable CEL that would ultimately occur because the AFR MAP tables were not recalibrated to recognize the new high flow intake and/or exhaust.
So the bottom line is that if change any of the original ECU calibrations your 5yr/100,000 mile powertrain warranty is voided.
Burning Brakes
Joined: Dec 2007
Posts: 1,015
Likes: 1
From: Maryland
St. Jude Donor '08
Anything you change to the engine that affects airflow requires a tune, no excpetions. Deleting cats and rear O2's requires a tune. Brand is irrelevant. This topic pops up from time to time and so does my explanation because internet myths need to be kept in check. Your engine maintains stoic a/f ratio within a -14/+24% range and when you go outside that range you get a CEL. Anyone and everyone who changes an aircleaner or exhaust parts changes the airflow and thus changes the part throttle fueling. If a person says he installed headers and didnt get a CEL, that doesnt mean his car is running correctly, it means he can be at +23% and way off on WOT fueling so its far from optimum even without a CEL.
So the reason you have the CEL is because it is running lean at part throttle and as a result of that, you are running grossly rich at WOT. Long term it damages the car to not have the fueling right.
The tune will violate the warranty. If thats important to an owner, dont mod.
So the reason you have the CEL is because it is running lean at part throttle and as a result of that, you are running grossly rich at WOT. Long term it damages the car to not have the fueling right.
The tune will violate the warranty. If thats important to an owner, dont mod.
Can you be more specific as to how the engine would be damaged from simply installing LT Headers and NOT recalibrating the AFR MAP tables?