Difference between front and rear O2 sensors?
06-26-2011, 03:17 AM
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Difference between front and rear O2 sensors? Is there any difference between them? The only differences I could tell were the wire lengths.
I'm putting in LTs and deleting the rear O2s from the system, so are they useless now? or could i use them for the front if I needed?
I'm putting in LTs and deleting the rear O2s from the system, so are they useless now? or could i use them for the front if I needed?
06-26-2011, 04:00 AM
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They are different, the front O2s are used by the ecm to measure the fuel/air in the exhaust to aid in tuning the engine to the right fuel/air mixture when it is running, for example if the engine is running rich, the front O2s will notice that and the ecm will adjust the injectors to compensate. The rear O2s are just there to make sure the cats are working, when you put long tubes in like you are you have two options. You can get the rear O2 codes tuned out of your ecm which will keep the SES light from coming on and not letting you pass emissions. The second option you have is to use O2 sensor simulators, which basically trick the ecm into thinking the rear O2s are working properly. Depending on where you live, they may have visual inspections at the emission test, so I would check that before you through in long tubes, if you don’t have it then the two options I said will work fine. And to answer your question, you can not use the rear O2s to take the place of the front ones. If you do install long tubes, you will need to get O2 extensions in order for the front O2s to reach the bungs in the long tube headers. Hope this helped and good luck.
06-27-2011, 08:50 AM
#3
They are different, the front O2s are used by the ecm to measure the fuel/air in the exhaust to aid in tuning the engine to the right fuel/air mixture when it is running, for example if the engine is running rich, the front O2s will notice that and the ecm will adjust the injectors to compensate. The rear O2s are just there to make sure the cats are working, when you put long tubes in like you are you have two options. You can get the rear O2 codes tuned out of your ecm which will keep the SES light from coming on and not letting you pass emissions. The second option you have is to use O2 sensor simulators, which basically trick the ecm into thinking the rear O2s are working properly. Depending on where you live, they may have visual inspections at the emission test, so I would check that before you through in long tubes, if you don’t have it then the two options I said will work fine. And to answer your question, you can not use the rear O2s to take the place of the front ones. If you do install long tubes, you will need to get O2 extensions in order for the front O2s to reach the bungs in the long tube headers. Hope this helped and good luck.
Anyway I honestly do not know the answer to that and am curious myself. I ended up throwing my rear o2's away thinking they were useless... but now I wonder if they would work if you plugged em in the front with the front harness. I want to say they are the same, because in my old car I ran vette rear o2's in my front... so if vettes the same i'd imagine so are f-bodys? Idk.
06-27-2011, 11:58 AM
#5
Correct for the most part. The rear O2's are heated but they still function the same so you can use them for the front. If you wanted to spend a little more you could get the vette O2's which have a much faster switch rate making them more accurate but thats not a big deal unless your car is heavily modded.
06-27-2011, 08:47 PM
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12-27-2012, 09:00 AM
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Your car will run the same, but don't be surprised if the sims don't work and you get a service engine light. You should really get a tune when you can with the rear O2s deleted in your computer. A mail order tune is cheap and will better fuel your motor with the headers and off road y pipe. This will make a great difference in the way your car runs, to the good side though. People always do mods with out properly supporting them and it ends costing them more in the long run.
02-03-2013, 08:41 AM
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Your car will run the same, but don't be surprised if the sims don't work and you get a service engine light. You should really get a tune when you can with the rear O2s deleted in your computer. A mail order tune is cheap and will better fuel your motor with the headers and off road y pipe. This will make a great difference in the way your car runs, to the good side though. People always do mods with out properly supporting them and it ends costing them more in the long run.
04-23-2016, 06:02 PM
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Ancient thread, but since it's back....
I've used sims in many LS1 applications, both early and late PCMs, and they've always worked just fine to keep the SES light away for me. If you still get a light for the cats/rear O2s, then the sim is damaged. Only issue I've ever seen is that the "heated O2" readiness test won't complete with sims. This may or may not be an issue depending on local testing requirements.
I've used sims in many LS1 applications, both early and late PCMs, and they've always worked just fine to keep the SES light away for me. If you still get a light for the cats/rear O2s, then the sim is damaged. Only issue I've ever seen is that the "heated O2" readiness test won't complete with sims. This may or may not be an issue depending on local testing requirements.
