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O2 Sensor Question

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Old Dec 21, 2005, 02:23 PM
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O2 Sensor Question

Ok, so I've searched and found nothing to answer my question. What happens if you just cut the wires on your back 02 sensor and just leave it like that? Since it doesn't affect engine performance or anything like that whats the use for it besides to plug the damn hole. I'm saying this becasue I used the spark plug defowler trick and it rubbed my damn 02 sensor against the body of my car and the sensor broke. I'm talkin wires were disconnected and all...so I just cut the wires and screwed it back in the cat delete. Is this gonna hurt my car at all? Thanks, Kevin
Old Dec 21, 2005, 02:31 PM
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bump for a needed answer by 5...
Old Dec 21, 2005, 02:37 PM
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answer my question!!!!!!
Old Dec 21, 2005, 02:45 PM
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if the sensor is not plugged in it, the ECU will default to running rich as a safety precaution.


yes, the car will run. yes, the car will run rich. it really wont hurt anything, just make sure that the wires are not simply cut, but that you cover the end such that the +5V (or +12V whichever it is) wire doesn't ground out and short something.
Old Dec 21, 2005, 02:47 PM
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oh, and you most certainly will get a CEL. but that may not matter much if your running a cat delete anyway...
Old Dec 21, 2005, 02:57 PM
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You will get a CEL and if the wires are naked and left hanging they will short and blow the 10AMP engine fuse. Don't ask me how I know. Its not fun when your car is going 65mph on a 4 lane highway and all of a sudden your engine dies, you steering become stiff and your brake pedals become stiff.
Old Dec 21, 2005, 03:14 PM
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While were on the o2 sensor issue. I installed a full 3" TBE (Tanabe down pipe, cat delete/ Magnaflow resonater and a Magnaflow muffler) but haven't had the time to install the perrin o2 device (sends a signle to eliminate the codes). Could that be causing my car to run slightly rich, being that the ECU thinks the cat isn't working properly? I sthere an easier place to locate the o2 device besides tearing into the dash area/ center tunnel?
Old Dec 21, 2005, 03:15 PM
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LOL, I already blew the 20(ahem) amp engine fuse...I just ordered another one...What a headache. Thanks for your help. But As i mentioned before, The back sensor shouldn't
affect engine management AT ALL...right. So it shouldn't affect my A/F ratio right?
Old Dec 21, 2005, 03:18 PM
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Sgt, you have no cat and that is why you are throwing a code...the only function (as far as I know) of the back o2 sensor is to make sure your cat convert is working properly. Since you don't have one, all that gunk is getting to your o2 sensor and throwing your code.
Old Dec 21, 2005, 03:31 PM
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Originally Posted by DaWorstPlaya
You will get a CEL and if the wires are naked and left hanging they will short and blow the 10AMP engine fuse. Don't ask me how I know. Its not fun when your car is going 65mph on a 4 lane highway and all of a sudden your engine dies, you steering become stiff and your brake pedals become stiff.
wow...that is funny (well not really) the same thing happened to me when I was driving to RIPP when I was having my galant fixed, and I ran over a cargo strap on the BQE and it ripped my o2 sensor wires out, (because i had a very poorly designed header system and my o2 sensors hung really low) and as i was crossing the verazano bridge my car just died....HOLY FREAKIN SCARED. thank god i had already got over the apex of the bridge and i coasted to the tolls.
Old Dec 21, 2005, 03:35 PM
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Originally Posted by Kbp2025
Sgt, you have no cat and that is why you are throwing a code...the only function (as far as I know) of the back o2 sensor is to make sure your cat convert is working properly. Since you don't have one, all that gunk is getting to your o2 sensor and throwing your code.
true..the back o2 sensor has nothing to do with your engine managment. it is purely an emissions thing and to sense whether or not your cat is there. Ultimate Racing has a test pipe that has a j-tube that relocates your stock o2 sensor so it doesnt see the blunt of the exhaust from the engine. so essentially is gets hot and senses just enough exhaust so it doesnt throw a CEL. I have had my car set up like this for almost 2.5 years with no CEL.
Old Dec 21, 2005, 03:46 PM
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Originally Posted by Kbp2025
LOL, I already blew the 20(ahem) amp engine fuse...I just ordered another one...What a headache. Thanks for your help. But As i mentioned before, The back sensor shouldn't
affect engine management AT ALL...right. So it shouldn't affect my A/F ratio right?
i would imagine if the ECU thinks the CAT is damaged or the rear O2 sensor is bad, even if it doesn't use it for fuel adjustments, i still think it would run in rich mode for protection. a manufacturers thinking is better be safe then sorry. buuuuut i don't know for sure and very likely could be wrong.
Old Dec 21, 2005, 03:49 PM
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Well Either way, I already got a new sensor on the way...(can't stand that CEL) But thanks for all your help guys. Kevin
Old Feb 8, 2006, 08:04 AM
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what if you cut the wires on the o2 sensor and installed an o2 sim? will you still get a cel?
Old Feb 8, 2006, 09:12 AM
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any time the emmissions devices are not working/signaling the ecu the engine will be put in the old "DSM limp mode" running really rich and all kinds of timing pulled



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