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Discussion Starter #1
I need some help troubleshooting my upstream o2 sensor on my 9th gen si. When I watch the voltage for the o2 sensor it jumps from 0 to five rapidly. It doesn’t fluctuate in between. Does that mean it’s bad. Wanna troubleshoot before I buy a new one. ( I was reading it on my Hondata)
 

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I need some help troubleshooting my upstream o2 sensor on my 9th gen si. When I watch the voltage for the o2 sensor it jumps from 0 to five rapidly. It doesn’t fluctuate in between. Does that mean it’s bad. Wanna troubleshoot before I buy a new one. ( I was reading it on my Hondata)
Jumps 0-5 what?

Why do you want a new one?
 

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Kinda curious, are the stock 0² sensors narrowband? May be the OPs observation.

I noticed after Hondata tune, when I hit the Steering wheel button that makes the tach show the air/fuel ratio, that it jumps high to low...never runs in-between....leads me to think it's narrow band, but just a guess.
 

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Discussion Starter #4
When I’m viewing my o2 sensor through the Hondata app it shows 0v or 4.96v but nothing in between it just moves back and forward. I figured it should gradually move but their are no no numbers in between just 0 or 4.96.
I don’t mind buying a new one just wanna make sure it’s the o2 sensor.
Also my AEM wideband reads 15.7 to almost 16.0 while at idle but when I start cruising it starts going back to normal(14.7-14.8).
The Air/fuel ratio on the Hondata app reads normal at idle but my AEM says different.
I do have a comptec supercharger on it and don’t really want to boost unless I know it’s safe.
Thank you guys for the reply.
 

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The stock o2 sensor is wideband. If the AF corrected is showing correctly and similar to your AEM then you are fine and there is no problem.

Also, what sensor at you monitoring for voltage? I don't see a parameter for the o2 sensor voltage within flashpro.

Also if your stock o2 was failed that badly, pretty sure you would trip a CEL.

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Discussion Starter #6 (Edited)
So it might not be a o2 sensor problem then. I just don’t want this car to go bad like my Subie just did. It’s just weird that it idles lean but when I start driving it corrects itself. Don’t know what to trust it never did this before.
While my AEM is saying I’m running lean the app says it’s fine so should I just go based off the app and not the AEM sensor? I’ve been looking at the sensor I circled in blue
 

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Not really familiar with the app but I believe what you circled is for an aftermarket wideband wired into hondata so it's not tell you anything.

Do a datalog and look at AF Corrected, this the a/f ratio your primary o2 is reading.

Who tuned the vehicle? they should be able to help you of there are concerns about how your car is running.

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Discussion Starter #10
I was thinking the o2 was out because of that sensor reading but that’s not it. I was just getting different reading between my AEM sensors and the Hondata app. I just don’t need to run lean and replace the motor. The AEM says it’s running lean at idle but the app says it’s fine. But the AEM does show normal while cruising just not at idle. I haven’t boosted since this problem started. Trying to figure out what is doing this. No problems with the vehicle other than this issue.
 

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I was thinking the o2 was out because of that sensor reading but that’s not it. I was just getting different reading between my AEM sensors and the Hondata app. I just don’t need to run lean and replace the motor. The AEM says it’s running lean at idle but the app says it’s fine. But the AEM does show normal while cruising just not at idle. I haven’t boosted since this problem started. Trying to figure out what is doing this. No problems with the vehicle other than this issue.
Gotcha.

WIdeband O2 sensors(AF sensors) are extremely accurate ,and because of this, the PCM is much more able to precisely meter/trim fuel.

Consequently, AF sensor voltage appears fairly static and the excursions are too minute to view on the voltage scale. So it becomes necessary to monitor these sensors via current. A good scan tool will display the AF sensor reading in milliamps(mA), just like the factory scan tool does.

The data displayed by Hondata and other Apps is fairly generic, and for the most part,subpar quality in terms of vehicle diagnostics.

As to whether you're really running lean or not, the fuel trim values should be used to make that determination....
 
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