Are the rear O2 sensors a must?

Just installed my Pacesetter LT's and will be getting the rest of the exhaust welded up tomorrow. I know that running the truck without the rear o2 sensors, or without the cats will throw the SES light, since I don't have a custom tune. My question is, what is it going to do besides throwing a code? Reduced performance, gas milage, etc.? From what I've read, they just check the efficiency of the converters, correct? I just don't want to have the cats re-attached, only to remove them when I can afford a custom tune. I can live with the SES light if performance and gas milage isn't being lost. Thoughts? And no, I can't afford a custom tune right now?

it wont hurt anything, just ses, and casper electonics makes 02 simulators that will get rid of the ses. just a thought. tune would be best tho.

The problem I have is that if something "important" goes wrong to turn on the light, you won't know 'cause it's already on.

+1 you could **** some stuff up and not know it.

So there is no negative effect on horsepower or milage? I've been searching and reading all morning. Someone said they used sparkplug defoulers to pull the O2 sensors out of the exhaust a little and the light went off. I would like to buy a used set of O2 sims or something to fix it temporarily until I can afford a tune. Also, I agree with you that something might go wrong and I won't know since the light is already on. I gotta figure something out soon though.

Had my LT's on for a few weeks with no problems. Just can't afford a tune right now. If there is a major problem, the engine light will flash rather than be solid. Or just stop by an autozone once a week if there is one and get the scanner put on for free just to check.

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Originally Posted by tanz45

If there is a major problem, the engine light will flash rather than be solid.

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So this is true? Also, I can clear the codes and/or read them with my superchips tuner. They will come back on within a few minutes, but I guess I could at least keep a check on any other codes.

Yes, it will flash if there is any major damage because this a warning that you are hurting the emissions system. Your tuner doesn't have the option to disable the rear 02's or the codes?

Or find someone with HPTuner or some other software to turn them off. You may have to pay a licensing fee but it may be worth it to you just for that. Do it before the header install. Not too sure how far up into OK you are but I'm in Denton and to license your truck to turn the codes off will cost me $100 to do that or you can go to one of the other guys that are a little further away and can do some tuning tweaks for you later.

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Originally Posted by tanz45

Yes, it will flash if there is any major damage because this a warning that you are hurting the emissions system. Your tuner doesn't have the option to disable the rear 02's or the codes?

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The SES light only flashes when the PCM detects a misfire. There are plenty of other things that could go wrong and potentially be damaging that will illuminate the SES light but not cause it to flash. Best to take care of the SES light for the cats ASAP. Also, don't bother with sims or whatever. You'll probably want a tune with the headers anyway, just have the tuner disable the cat codes while he's in there.

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Originally Posted by tanz45

Your tuner doesn't have the option to disable the rear 02's or the codes?

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I think I can clear the codes, but they will come right back on I think. Anybody know if a handheld(superchips) will turn off rear O2's? I don't think they will.

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Originally Posted by RedHeartbeat

Or find someone with HPTuner or some other software to turn them off. You may have to pay a licensing fee but it may be worth it to you just for that. Do it before the header install. Not too sure how far up into OK you are but I'm in Denton and to license your truck to turn the codes off will cost me $100 to do that or you can go to one of the other guys that are a little further away and can do some tuning tweaks for you later.

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Is that HPTuners that you have? I am looking at splitting one of these with a friend. If we purchase the Pro version($649) can we tune both of our vehicles with the 8 credits it comes with, or only one VIN per software? BTW, only about an 1.5 from Denton. I'll have to come out there and race one night.

Yes, eight credits will allow you both to tune all you want, 2 each license, and then some. If you both have the same year model trucks you can get an unlimited license for 6 credits and be able to tune all the trucks in the world that are your year model. :rock:

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Originally Posted by thunder550

The SES light only flashes when the PCM detects a misfire. There are plenty of other things that could go wrong and potentially be damaging that will illuminate the SES light but not cause it to flash. Best to take care of the SES light for the cats ASAP. Also, don't bother with sims or whatever. You'll probably want a tune with the headers anyway, just have the tuner disable the cat codes while he's in there.

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+1

The only thing that causes a flashing light is a misfire constant and bad enough to cause potential catalytic converter failure due to meltdown from excess unburned fuel in the exhaust stream.

Yep, that happened to me. My cats failed. Now they r clogged.

I used my Superchips to clear the O2 trouble codes last night and went for a drive. I was expecting it to come right back on, but they still have not thrown a code yet. Does it take several cycles before the SES light will come back on?

Sometimes, yes.

+1

This might be a little late, but my solution to the after-cat O2 sensors is pretty low budget. After I put the LT's on, there was no bung for them in the ORY so I zip-tied the rear O2's to the transmission mount. Logically, if they are out of the increased pollutant flow, they won't detect the increased polutants. No codes for me..Then again where I live we have no emissions testing to sneak past.

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Originally Posted by fishoops

This might be a little late, but my solution to the after-cat O2 sensors is pretty low budget. After I put the LT's on, there was no bung for them in the ORY so I zip-tied the rear O2's to the transmission mount. Logically, if they are out of the increased pollutant flow, they won't detect the increased polutants. No codes for me..Then again where I live we have no emissions testing to sneak past.

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I am actually going to try something like this. I went ahead and left the cats off and was planning on getting some simulators(to no avail yet). I am going to try your idea first and then I have also read that people have used anti-foulers(for spark plugs) to extend the O2 sensor out of the exhaust stream somewhat and do not get a SES light. Thanks for the thought.