Hunting down lean condition P0139 Honda Fit 07

ltslimjim

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Not sure about your fuel economy but if the sum of STFT and LTFT is under 10%, I would say you don't have a lean condition or injector problem.

Maybe try wiggling the o2 sensor harness and see a drop out on the signal? If not, connection is fine and that is one off the list.

If all checks out fine, you do not have an exhaust leak, I would just replace the sensor with an OE o2 sensor. There are times aftermarket parts are not reliable. Not much to say for a code like this.
Thanks for all of your help.

I had a misunderstanding with fuel trims and looking for a reason for fuel economy drop along with this CEL in particular.

You’re right. The readings are normal. :oops:

I’ve been overthinking this.

But I would like to rule out air leaks and the wiring as you mentioned.

The trouble is, even if I wanted to try another sensor, the threads for this aftermarket converter got damaged before. I had forgotten. So, I think I’ll just live with it until another converter is needed rather than throwing several hundred at it to get the code to go away.
 

ltslimjim

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@Luftmasse

So, here is the update.

Solution: Replace cabin fuse

I replaced the fuse that was recommended in the video, and the light has stayed off for about 2,000 miles now. Go figure! Before it would throw the code on every couple tanks of gas.

Also, I was able to manage 35 MPG on several tanks while driving @ 75-80 MPH on a recent road trip. 1,500 miles round trip and no CEL.

Verdict: Resolved!
 
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@Luftmasse

So, here is the update.

Solution: Replace cabin fuse

I replaced the fuse that was recommended in the video, and the light has stayed off for about 2,000 miles now. Go figure! Before it would throw the code on every couple tanks of gas.

Also, I was able to manage 35 MPG on several tanks while driving @ 75-80 MPH on a recent road trip. 1,500 miles round trip and no CEL.

Verdict: Resolved!

LOL Bro.
Sometimes we try too hard.
It has to be a great feeling now.
 

ltslimjim

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LOL Bro.
Sometimes we try too hard.
It has to be a great feeling now.
Well, along the way I learned a little more about some things, which previously I only had beginner level information about, from knowledgeable posters like @Luftmasse !

That’s what makes BITOG a place I enjoy. Sure, maybe I’m still a novice in areas, but gotta start somewhere. 🤷‍♂️😜

My OCD now has me thinking…if these cabin fuses are getting all corroded without breaking, I wonder what other ones are worth changing and why not just change them all out for peace of mind? 🤣
 
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