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Hello just got a check engine light and the scanner is reading p0139 as a code. I looked it up and I’m seeing it’s going to be a sensor but I’m not sure which one and where it goes. If anyone has done this before all the help out he appreciated. Thanks in advance.

 
Rep Power: 125

I think it's the O2 sensor that sticks out of the exhaust manifold.

 
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Hmmm i probably should mention that i replaced the up stream af sensor ( it’s a 05 dx so it needs the af) but I don’t remember the code it was throwing last time. Do you think the new sensor failed?

 
Rep Power: 125

Did you buy an OEM sensor? If not, then it's probably failed.

 
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no it was a denso sensor which is used by Honda from the factory (from what I’ve been told) I could always get a new one under warranty too

 
Rep Power: 125

Denso is OEM. Where did you get it from?

 
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I got the link from a member on this forum as I know there are multiple fake ones. Even checked with others to see if it’s fake or not.

 
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Okay I’m going to give this alittle bump cause I haven’t got a response. There are 2 sensors attached the the manifold the one just after the exhaust manifold and the one after the cat. I replaced the one just after the manifold but I’m wondering if this code is coming from the other sensor? Any help would be appreciated

 
Rep Power: 125

Edit: quick search shows that the one under the car is the culprit.

 
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hmmm that’s funny that’s the one I replaced. It’s still diner warranty so I’ll try to get a new one

 
Rep Power: 125

I edited my old post.

 
Rep Power: 367

https://autoservicecosts.com/obd2-codes/p0133/

https://www.yourmechanic.com/article...ank-1-sensor-2

 
Rep Power: 367

How to Fix

1. Check and repair exhaust leaks.
2. Check wiring problems such as shorted or frayed wires.
3. Check both the frequency and amplitude of the O2 sensor.
4. Check for worsening or contaminated O2 sensor, replace if required.
5. Check for inlet air leaks.
6. Check the MAF (Mass Flow) sensor for the right operation.

 
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Which o2 sensor are we talking about?

 
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The fault code is for the secondary O2 sensor. Not the one on the exhaust manifold but further down.

 
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great thank you that’s the answer I was looking for

 
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well I got a laugh out of this and I hope you guys do to. Went online searching how to replace the sensor and I go under the car to look at where it is. Well I go under and I’m looking and looking and looking. Still can’t find it. Look at the video and it’s right under the front sway bar. Well apparently I don’t have one lol. The exhaust is shiney and new after the place where the cat is supposed to be. Good thing I don’t have emissions testing lol

 
Rep Power: 367

so, previous owner removed the cat?

 
Rep Power: 0

yeah it looks like he did