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HIT EM UP F0000000
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2,613 Posts
^U really dont need one,also u leaving 15 dollar deposit,and then u get it back as a return,i took my o2 off with the funky looking wrench!
 

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Banned
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1,805 Posts
Discussion Starter #23
Use a flared wrench, I used a standard long wrench and broke loose with ease.. Just give it a good whack with a hammer and it will break free.

"There are a couple of vendors out there that provide a small device called O2 mimick or some kind of name used to plug into the harness connected to the ecu. This device provides the correct amount of resistance to "fool" the ecu into thinking there is a properly working O2 sensor there."

- well I just gave you enough info so that you dont need to BUy anything but 1 resistor and some solder

"btw, nice writeup Danny. I just ignore the code since I know why the ecu is throwing it.
And I've passed emissions twice now (a span covering 4 years)"

- Well now you can get rid of that damn light :D , and I believe that the 2nd cat is also a 3 way cat and lowers N0x and co2 among others. In theory, any CLEAN running engine should pass emissions with no cat (except in cali) All the cars ive seen with hollowed out cats, believe it or not were STATE INSPECTORS but just for shits and giggles did the emissions on their cars and they passed !!! not by too much though.

"So, this should, in theory, work for someone running a test pipe, correct? Basically fooling the ECU into thinking there's a cat there."

- Well, this is a fix for people who've removed their primary cat at the manifold. By saying test pipe, you mean taking out the downstream cat and placing an empty pipe in there, I have no idea. All I know is that this will fix the p0420 code when you remove the pre-cat (primary cat). If you think about it, there is no oxygen sensor after the downstream cat, so I dont know if youd get a MIL after installing a "test pipe". How would the ecu know the readings after the downstream cat, to know if its working properly?? Anyone every got a CEL after installing a "test pipe"... Sorry, I dont know about the 2nd cat
 

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Official Troll
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7,780 Posts
It's not that all that complicated. Your first o2 sensor reads the oxygen content of the exhaust right out of your ports. This is the o2 sensor that controls the A/F ratio, making sure that the mixture is 14.7 to 1 (I think) . This is the ideal mixture for max catalytic converter efficiency. The 2nd o2 sensor takes the oxygen reading after the exhaust has past through the exhaust manifold catalytic converter. This sensor is only there to tell you if your cat is working properly. If the 2nd o2 is reading a different oxygen measurement that then 1st o2, congradulations, your cat is functioning. but if the 2nd o2 is providing the same reading as the 1st o2, then you'll be thrown the "service engine soon" light.

My check engine light has never come on because I've relocated the 2nd o2 downstream of the 2nd cat.
 

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I AM LEGEND
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10,874 Posts
I just printed out your fix,my shop will have to look it over tomorrow.If they say its all good,then fawk getting a cat,I will just throw a resonator under there and have them do the install.
 

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I AM LEGEND
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10,874 Posts
This trick does work.Just got my HS header installed and used the resistor in line and no CEL yet.

I am going to request this be FAQed.


Thx Danny.
 

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3 Posts
no I Cut the black wire on the 2nd oxygen sensor and I placed the resister "in line" or in "series" with the black wire

Black wire ---------------------------- X cut X------------------------

--------( | | | | )------ 1.2k

Black Wire with resister is series:

o2 harness--------------------------( | | | | )------------oxygen sensor
inline is in series with the black wire.
 
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