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O2 Sensor Fix

Provokr

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Joined
September 1, 2007
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City, State
Jacksonville, NC
Year, Model & Trim Level
2005 XLT 4.6L 4X4
How many people need info on bypassing the sensor portion of their O2 sensor so they can get rid of their Check Engine Light and pass their state inspection due to a bad sensor or bad cats? I can make a good write up if it is needed.
 



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>>>>>>>>>
How many people need info on bypassing the sensor portion of their O2 sensor so they can get rid of their Check Engine Light and pass their state inspection due to a bad sensor or bad cats? I can make a good write up if it is needed.
>>>>>>>>>>>

I do not need any CEL/O2 sensor help ATT, but you should post your suggestions anyhow so that it will be in the archives when someone does need that kind of help and they can find it thru the search bar on the main web page.
 






Okay, I wish I had this when I needed it so I am going to make it for anyone who has an explorer and is smart enough to search this forum.
Obviously you have a problem if you have replaced all of your O2 sensors and you are still throwing a code. Chances are that one of your catalytic converters are bad and if you have 3 catalytic converters like I do, that is not a cheap fix. You probably had the guts of one of your cats fall apart and clogging the last one that they both feed into. You probably want to get that fixed eventually, but if you are in a bind and have to get rid of your check engine light due to an emissions code (P04XX Auxiliary Emission Controls) you can try this to fix it.
Pretty much what this mod will do is give the attenuation values that the ECU is looking for(the capacitor is a +/- 20% component, the resistor +/- 5%). The input voltage measurement at 1.0Hz is due to the loading effect of the capacitor as the input frequency approaches the turnover frequency which is what tricks the ECU and gives it the resistance it's looking for.
So, now you want to know how to do it: I don't have a lot of pics, but the ones I do have are very effective and you should have no questions.
1) Go to Radio Shack and buy the following:
Qty 2: P/N 272-1434 (1 Micro Farad capacitor +/- 20%)
1 pack of P/N 271-1134(1 Mega Ohm 1/2W +/- 5%) you can also use the 1/4W if they don't have the 1/2 in stock. They sell these resistors as a pack of 5
If you don't have flux, solder, a soldering Iron, or heat shrink, you might want to buy that at the time too.
2) Get home and disconnect your rearward O2 Sensor's plug from the harness. More than likely you have 2 of them so be sure to look. There are 2 main set-ups with the 3rd gen:
1. 2 cats located on either side of the Ypipe, (an O2 sensor before and after this primary cat) and a resonator shortly after. then the factory muffler. and 2 1/4'' pipe out the back. ( 02-03 )
2. 2 cats located on either side of the Ypipe, (an O2 sensor before and after this primary cat) with no resonator, then the factory muffler then 2 1/4'' pipe out the back. ( 04-05 )
Just follow the O2 sensor up to where it disconnects and disconnect it.
O2location.jpg

3) Remove your negative battery terminal so you can reset your computer while you are doing this project
4) Remove your O2 sensor(s) from the y-pipe and bring them inside. I used a 7/8" wrench but there are special "O2 Sockets" out there. It is just a socket with a slit in the side so the harness can stick out of it. It just depends on how easily accessible your sensor is.
5) Here comes the fun part!! Leave the 2 white wires alone!! Pull back the insulation sleeving so you can access the wires. I would not cut it off since it is a high temp covering and it will prevent your wires from getting burned if they come in contact with any exhaust components. Cut the Grey and Black wires somewhere in the middle. I understand most people do not have access to the kind of splices I do so you can make it look like the following picture and solder the wires after you are done. Just imagine the top wire is grey and the bottom is black and make sure you put heat shrink over the wires before you solder so you can slide it over and heat it up. You want to make this weather-proof and so that the wires don't touch each other.
Notsogood.jpg

Here is the actual diagram of what you are doing:
O2Bypass.jpg

This is what mine looked like after I was done:
photo.jpg

and then after I put the environmental sleeving on:
photo3.jpg

Once you are done, slide the factory fiber wove wire shielding back over it and you will never be able to tell anything had ever been done.!!
6) Plug your sensor(s) back in and tighten your O2 Sensor back into your y-pipe.
7) Don't forget to reconnect your negative terminal back to your battery
**Note** If you are doing this for inspection purposes make sure you drive your vehicle for 100 miles before you take it to the inspector or they will tell you to go away and come back after those miles have been driven
 






Great instructional post. Would be interesting to know if this method is effective on other makes of vehicles.
 






Great instructional post. Would be interesting to know if this method is effective on other makes of vehicles.
Thanks Rick!! I heard that the computers after 2003 got smarter and this mod could possibly not work because it is looking for a different kind of attenuation but I know for 100% that it will work on any 4.6 2003 and older. It's just a matter of finding what your computer is looking for.
 






Thanks for the response Provokr. Is there a way to determine what a vehicles ECU is looking for? How did you get the proper values for the EXP?
 












I am not seeing the pics can anyone tell me where to find the pics of the wires
>>>>>>>>>>>>

I can see the pics of the wires right here on this web page along with his post. You may have a problem with your PC being able to see the pics.
 






























If you are in a bind with a bad catalytic, I can see this as a temporary crutch to hobble through an inspection...but if it is the sensor, why not just send the few extra dollars to fix it properly?
 






I would think an emissions test would still fail if the cat was bad. Just a thought. I also agree that it should be fixed the right way. There also could be damage to the engine.
Just an old farts opinion.
Bob T
:us:
 






If only an o2, replace it if its a cat it should work.
But, to be honest, this is illegal as hell. It is afeferal crime to disable a pollution control device with the intent to defraud the government in an attempt to obtain a tag.
I'm not trying to start a fight, so take it as it was given.
We get a couple of posts on our local car club site a year, about similar situations.
And the answer is the same every time. If you are trying to do this to get a tag, be prepared to talk to the Man.
Greg
 






there are some places that don't require an emission testing and they usually gut the cats outs or replace them with straight pipes. to remedy the check engine light issue they have to resort to this mod, or a bung or diodes.
 






Would it not be easier to simply remove the bulb then. This would alter the running conditions of the motor. The ecu will think is getting the the right signal from the final o2 sensor, if it isn't running right that can't be good. If its just rid yourself of a CEL, why bother? Am I missing something? But if you tried that around here(suburban Atlanta), they are not going to let you register. Hell if the computer shows no codes but the CEL will not light with the key on but engine off...fail. If the gas cap doesn't pass, fail. If the ecu has no stored codes but you have recently disconnected the battery, fail.
And the is a 5 years or $50000 fine for fraud in acquiring a tag.
Some counties south of the city don't require emissions though.
Greg
 






So I guess you don't understand what that O2 sensor is there for - right? So you probably don't understand that your ECU adjusts the fuel mixture based on what the O2 sensors say - right?

Seriously dumb....
 






Wow...
So you are saying that the DOWNSTREAM o2 sensor adjusts the fuel injectors to maintain the proper fuel ratio based on the amount of free oxygen in the fuel stream, after the cat?
Here all this time i thought the 2 upstream ones did that,before the cat. Guess i need to study more then , huh?
Does change that this thread has been hijacked, or that in certain jurisdiction's,doing this could garner you some serious trouble.
Oh and be nice, I've never been anything but on this forum.
Greg
 



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So I guess you don't understand what that O2 sensor is there for - right? So you probably don't understand that your ECU adjusts the fuel mixture based on what the O2 sensors say - right?

Seriously dumb....

the downstream O2 sensors doesn't do anything to your ECU, it's the upstream that tells it to lean or rich the condition. they just merely tell you that you're polluting the environment since the cat is not doing its job.
 






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