2nd O2 Sensor

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4DRB16A

Senior Member
Ok here is what is going on. When my car warms up and the CEL light comes on it will idle up and down from 1000rpm to 1500rpm. I have cleaned the IAC.

Before I posted this I did some serious searching and found diagrams and the correct ecu pinouts to hook up the 2nd O2. The guy who did my swap did not hook up the 2nd O2! So I ran a wire (thick speaker wire) from the 2nd O2 to my ecu pinout C8. Still got the CEL.

So then I heard you can just splice your 2nd O2 into your primary. So I did this and the CEL STILL came on! So I came to the solution that it was a bad O2. I went to autozone and picked up 2 Bosch O2 sensors and I got the 2nd O2 installed but I couldnt get the O2 socket wrench onto the primary it wouldnt reach due to the block was in the way and also the heat shield on the underside of manifold.

So I figured that I installed the one that was throwing the code 2 and it should fix the problem. I drove it on the highway for a bit thinking it was fixed and the damn CEL came on again!!!

The only thing I can think of is that it is not getting a good connection to the ecu. The only way I could get the wire to fit in slot C8 is I went to Ace Hardware and bought a metal speaker wire connector and cut off the end and stuck the metal piece in the ECU slot. This should work good enough right? If not then what can I use to plug it in the ECU?

Thanks!!
 
Somebody has to know this answer. I have posted it in another forum with no response. It is a 4Door 91 Civic EX w/B16A OBD0.
 
You shouldn't have a secondary O2 you should only have one wich is heated O2 sensor. What code is the ecu throwing might be somthing else not just the O2 sensor i dont have mine hooked up and its not idleing up and down thats a vaccum leak some where in the hoses that hook up to the intake manifold check and see what codes the ecu is throwing and ill be able to better help you from there.


ya boy steveo
 
Originally posted by 96CIVICLS@May 1 2005, 05:09 AM
You shouldn't have a secondary O2 you should only have one wich is heated O2 sensor. What code is the ecu throwing might be somthing else not just the O2 sensor i dont have mine hooked up and its not idleing up and down thats a vaccum leak some where in the hoses that hook up to the intake manifold check and see what codes the ecu is throwing and ill be able to better help you from there.


ya boy steveo
[post=493575]Quoted post[/post]​
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It is flashing 2 quick times which is Code 2. Secondary O2 sensor. It doesnt idle up and down when it is cold only when it gets warmed up then it idles erratically and the CEL comes on.
 
Anyone know where I can get the correct ecu pinouts so I know it is getting a solid connection to the ecu?
 
Go to the junkyard and pull some ecu pins,in my car I used some harness pins to do my vtec into the ecu and no luck,tryed everything and the wire showed connectivety[?] but as soon as I put the right ecu pins on it worked fine,and the pins looked very similar but there is apperently that big a difference.
 
your not looking at the right list of codes. OBD 0 doesn't even list a sendondary O2 sensor.
 
Alright guys I am STILL having this problem. I have come to the solution that it is a clogged cat conv. I am going to get my exhaust put on with a carsound cat and see if that solves the problem.
 
go to the junk yard and cut out some ECU plugs. I'm guessing it's not making good enough contact. get the correct pin and run the 2nd o2 directly to the ecu.

to the people saying that there is no 2nd o2, if you read this again since you posted back in may, STFU!!! if you don't know what your talking about, don't say shit.

https://hondaswap.com/forums/index.php?...type=post&id=31
 
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