P0139 error

I need some help here. I've been searching everywhere and I can't seem to find a solution. I have a 2018 Honda Civic si with full 27won bolt ons including their w1 bolt on turbo, Injen intercooler, CNT racing intercooler pipes. I also have a Sirimoto flex fuel kit. So shortly after installing my 27won down pipe and front pipe I started to get the P0139 exhaust system error code so when I flashed my basemap for the W1/flex fuel setup I disabled the secondary O2 sensor but after 10k of driving I started experiencing loud sporadic banging coming from my exhaust and sometimes even sounding like it came from the motor. When I checked my sensors I would experience 2-3 knocks as well. It got to the point where I was afraid to push the car because I didn't want to blow it up. So I went and reflashed the basemap again with the sensor enabled and the banging eventually went away and I get maybe 1 knock here and there versus 2-3+ when I had the secondary O2 sensor disabled but the problem is that I still have the CEL and I'm trying to figure out a way to disable the code. It's been a nightmare trying to figure this out. I can't find it under misc or closed loop. How can I disable this code through Hondata? I need step by step if at all possible.

I think the best you can do is get a datalog when the problem occurs and have someone here, hondata forums to analyze it. You can also send your datalog them.

NikkoPH said:

I think the best you can do is get a datalog when the problem occurs and have someone here, hondata forums to analyze it. You can also send your datalog them.

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I'm kinda just looking for instructions on how to disable the code. Apparently from everything I've researched, it just needs to be disabled.

oO Mr Robot Oo said:

I'm kinda just looking for instructions on how to disable the code. Apparently from everything I've researched, it just needs to be disabled.

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Yes, you should be able to disable the code from the calibration. Save the calibration and upload.

P0139 is not a dangerous issue. Your O2 sensor is not seeing enough exhaust gas to make it happy. If you have an adjustable de-fouler you can move the sensor more into the exhaust stream. If this is not possible, check for a P00139 disable within Hondata. I know I have seen it in other tuning software.

360glitch said:

P0139 is not a dangerous issue. Your O2 sensor is not seeing enough exhaust gas to make it happy. If you have an adjustable de-fouler you can move the sensor more into the exhaust stream. If this is not possible, check for a P00139 disable within Hondata. I know I have seen it in other tuning software.

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I know the code isn't dangerous. I just don't want to disable the secondary O2 sensor cause it causes issues. Not sure if it's because my dp is catted but I'm trying to get instructions on where to disable the code from cause it's not under the misc or closed loop windows in Hondata.

old thread I know... I just got P0139 with a defouler on my CTR
I have a catted Graham Rahal DP so I think I just need to take the mini cat it came with out of the inside.. Its this one: https://jcarpart.com/products/90-o2...8yfnbng7dHt3ffO5sAYPwzqDse3zhuNhoCDXwQAvD_BwE

RRTypeR said:

old thread I know... I just got P0139 with a defouler on my CTR
I have a catted Graham Rahal DP so I think I just need to take the mini cat it came with out of the inside.. Its this one: https://jcarpart.com/products/90-o2-oxygen-sensor-spacer-engine-light-cel-check-bung-mini-catalytic-converter?currency=USD&variant=37547405639848&utm_medium=cpc&utm_source=google&utm_campaign=Google Shopping&gclid=CjwKCAjwsfuYBhAZEiwA5a6CDKUzDjxDji0yvJXBWtXVZk8yfnbng7dHt3ffO5sAYPwzqDse3zhuNhoCDXwQAvD_BwE

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I just installed the catless skunk2 DP + FP combo in my sport hatch 2 days ago and it came with a cat-less defouler. I still got p0139 so I don't think removing the mini cat would work in your situation. It might be a better idea to remove the nut attached to the defouler to let it sit deeper in the DP and catch more exhaust flow

k1ngsabag said:

I just installed the catless skunk2 DP + FP combo in my sport hatch 2 days ago and it came with a cat-less defouler. I still got p0139 so I don't think removing the mini cat would work in your situation. It might be a better idea to remove the nut attached to the defouler to let it sit deeper in the DP and catch more exhaust flow

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ill try that

That seemed to work this time and I passed. I flashed it to stock drove it for about 20 min without the check engine coming up and took it in. Thank god...

Will a catted Defouler make it read slow?

RRTypeR said:

That seemed to work this time and I passed. I flashed it to stock drove it for about 20 min without the check engine coming up and took it in. Thank god...

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Good to hear

I had to reinstall my stock Catalytic Converter and my issues went away