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Discussion Starter #1 (Edited)
(In the Subject, I meant to type "O2 sensor extender")

Happily for me, living in New Mexico has meant that even when my 2001 Insight 5M sprouted the Check Engine light with the code pointing to the second O2 sensor...and even living (for a time) in a metro area that required emissions testing...hybrids get pass anyway. So there's never been any regulatory pressure to get this seen to.

However, I've had the oxygen sensor extension/fitting for awhile and, just today, in conjunction with getting new front rotors and pads, I had it installed.

I started the car and drove from the shop to the nearby Subway. I was very pleased to see the Check Engine light off (clearing the code had been requested). Went inside to get my sandwich, came out to restart and resume the trip home. Typical of all of the warm restart stumbles that I had experienced ever since that light first came on (reporting this code), on light throttle acceleration the car bucked once...then carried on...to the familiar glow of the Check Engine light, showing that apparently nothing has changed, no successful fooling of the computer, no cure of that stumble.

So.....do I just continue to live with it? I'm out only a few bucks.
 

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Discussion Starter #3
Thanks for the quick reply. There's much I don't know about all this so, bear with me here. All this time I'd been under the impression from discussions here that this Check Engine code pointing to the O2 sensor was a) common and b) easily fixed with the extension. Your reply seems to indicate that while both of those points could well be true, I might be experiencing something more complicated, involving not just the location of the 2nd sensor in relation to the exhaust stream but the two sensors themselves. Correct?
 

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The whole reason you have the check engine light on is because there is a fault in one or both of the sensors you can’t add an extension to the sensor and hope the light goes out you have to fix or diagnose the problem first start with what codes you have and go from there


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Well, the spacer under the #2 sensor has fixed a bunch oh them for me. I can't remember any that haven't worked. I even fixed my Miata this way the other day.

Sam
 

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Regardless of what they're called, what they do is to move the O2 sensor physically farther away from the main exhaust flow in hopes of tricking the ECU into not throwing the P0420 DTC when you A HFC, or a trackpipe. While on some cars they do actually prevent the P0420 DTC from being thrown, they cause fueling problems on all cars 2001 and newer. The ECU uses the input from the rear O2 sensor to affect fueling in addition to simply monitoring the cat (as in 2000 and older cars). If you remove the rear O2 sensor entirely, mount it somewhere that isn't in the exhaust at all (don't laugh, I've seen it done), or even just move it out of the main exhaust flow, you'll develop strange fueling errors as the ECU tries to make the rear O2 see what it's programmed to achieve. The result of this is slightly worse fuel economy, a worse idle, and generally increased difficulty in getting the car tuned or other check engine light codes


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Xspeedracer,

In your initial post you did not explain what check engine light code you had. You stated that you just had a spacer/anti-fouler installed.

If you are sure you had a P0420, about 90% of the time a spacer will help cure this code. The spacer has to be on the second sensor. You indicated you had it installed by someone else, please be sure it is on the second sensor and they didn’t mistakenly install it on the first one.

The first 02 sensor effects fueling as you describe not the second sensor.

The second sensor basically monitors what is between the two sensors, the catalytic converter, not fueling.

A P0420 code is catalytic converter below efficiency.

A spacer on the second sensor moves the sensor out of the direct stream of exhaust and the code normally goes away. I know of approximately 5 cars that don’t have any guts in the cars and run a spacer and have no codes and run fine.

The check engine light can read as many as maybe 100 different codes.

Please have the codes read and confirm what it currently is and please report back.

Thanks,
Scott
 

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The second 02 sensor bung is where I have my AF gauge mounted. The second 02 sensor is mounted in a enclosed tube under the vehicle with an O2 "Fooler" installed. No codes, excellent running, and for many many thousands of miles.

I agree with RX Scott.

Willie
 

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Discussion Starter #9
Scott, I'm the OP, not Xspeedracer,

Honestly, the code was pulled (and the spacer ordered) so long ago that I don't recall the exact numbers...but the advice at the time was, as you note, to simply get the spacer. I'll have the code pulled again, jot it down and report back. Yes, I'm aware that there are many possible codes that can lurk behind the Check Engine light (and also aware, via long-ago history with Honda dealer Master tech), that "90% of Check Engine alerts are initiated by a pollution control issue, even down to the misfiring of one spark plug on two successive ignitions."

Yes, I had a local mechanic do it in the course of installing new front brakes. Short of standing behind him to make sure it was added to the downstream sensor, I can't testify to that....but the instructions (and the "playback" of them) was definitely to add it to the #2 sensor location.
 

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All this time I'd been under the impression from discussions here that this Check Engine code pointing to the O2 sensor was a) common and b) easily fixed with the extension.
Nope, it's the code pointing to the catalytic converter that is easily fixed with the extension. (O2 sensor spacer)
 

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Not my post originally, Scott as you know from experience the 02 sensor was not put in with a spacer by Honda originally so it is only a temporary bandage for the real problem which requires more diagnostic time to correct properly I do understand how the o2 sensors work but they are not expensive to replace either vs the cat I have always found good info on Identifix when I have something I can’t easy diagnose


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If you really believe that the #2 O2 sensor affects engine performance, please provide documentation.

Sam
 

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The rear is monitored by the ecm if it sets a code it will fail smog therefore it affects engine performance period both o2 sensors monitors must pass to not set a check engine light. If they don’t they set a code you pull the code and do the diagnostic and repair or replace the problem component there is a lot of info online but it comes down to fixing the problem by diagnostic checking


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Discussion Starter #14 (Edited)
Okay, the actual code is P0134 HO2S S1 CIRCUIT HIGH VOLTAGE/NO ACTIVITY

The supporting explanation reads:

Code P0134 indicates that the Bank 1, Sensor 1 O2 electrical circuit had no activity for a predetermined amount of time.

I've done some searching with that code here in the forum...which produced 15 years worth of references and discussion. Hard to know what to make of what. When I factor out the messages that reported P0134 appearing ALONG WITH other codes, it's still pretty confusing, esp when there was a POV that this code alone, in an Insight this early (mine's a 2001 5M) was a "phantom".
 

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Of course it sets a code. But that's ALL it does. The P0420 does not change engine performance. Sure you need to fix stuff when there is a problem, but in the case of a P0420 on an Insight the spacer "fixes" it. By your logic if there is no code there there is no problem, therefore the problem is fixed.

Sam
 

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Well now we know,,your first o2 sensor dead,and no spacer there going work,,order first o2 sensor or pm me for both in a set,,75 shipped good compare to one from Honda at about 157.00 piece,,do what you like but think we all try to explain the set up,,high voltage bank 1 is number 1 location.
 

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P0134 is the only code my 2003 Civic Hybrid ever set. I replaced the first O2 sensor and it was forever happy. It was kind of expensive, but easy to replace. It is the top sensor, above the cat, right behind the engine. I imagine a car could run pretty poorly w/o a good sensor there.

The spacer is for the common P0420 code. It doesn't sound like that is what you have.
 

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Yep Bank 1, Sensor 1. Your MPG will thank you after fixing this one! I'm sure it tanked.
Also just FYI, it takes a little bit after the code is cleared for this to pop back up. O2 sensor is heated up to temp and needs to be driven for typically a few minutes at temp before the code pops back up. (If that helps answer some questions)
 
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