I was dealing with (read: ignoring) the P0141 code in my 2007 base Fit until a week and a half ago, when I needed to get an emissions test done to renew my license plates. The short story is I wanted to fix it myself, but had to piece things together from the forum, and there was still an information gap that I couldn't fill from others' experiences. So I'm going to try to consolidate all of that information and fill the gaps here. This'll be useful for frugal DIYers, I hope.

Anyway, the long story ...

I had had this problem before, shortly after purchasing the car used, and took it to the Honda dealership to get it fixed that time. Remembering that it wasn't cheap, and my situation being that I don't like the inconvenience/inconsistency of shuttles much any more, I decided to have a go at doing the repair myself. Looking on this site and at other places, it seemed like a pretty straightforward job, with little monetary risk if things didn't go smoothly.

First, what part did I need? I found that this code relates directly to the downstream O2 sensor (thanks doctorJ), so ordered this O2 sensor and an O2 sensor socket from RockAuto. The total for me, shipped, was $78 USD ($105 CAD). I ordered it on a Friday and received it on the Tuesday, I think ... it was faster than I thought.




This is what I received. The socket is a handy accessory, for sure.

Having never done this type of work before (I change my oil and wheels) I didn't know where the part was located or how to replace it. I didn't take a picture of where it's located, but it's on the passenger side of the catalytic converter. There's a diagram here, and the O2 sensor is part 16 in the diagram (and also currently listing at $220). What I couldn't find for the Fit is where the cord connected in the car. In searching, I found in some Acuras that the cord entered under the front passenger seat, so I unbolted it and looked underneath ... there were some wires, but no harnesses or wiring that matched the O2 sensor's, and no access cuts through the carpet to tell me to keep looking in there.

The next logical place to look, then, was in the centre console, so I started with taking that out. First thing I did is remove the fasteners - a pair of Phillips head screws at the back, and a pair of those PITA clips in the front (I ended up breaking the one that wasn't already broken).




Screw location at the back of the console



Clip location (the actual clip had already been persuaded out at this point)

The next thing I had to contend with was the handbrake and getting the console around that. You have to remove a plastic "plate" to get it over the handbrake.




That's the little plate that comes out, where the arrow is pointing

The side of the plate closest to the handbrake unfastens pretty easily, but to get the further side out was trickier. I had to pull the plate towards the handbrake, and then wedge a standard/slot screwdriver in the little space that opens from pulling. Once it was in there, I encouraged it a bit further and it popped out.

Now I could get the console pretty much out of the way, but I still couldn't see where the wires led. I'd have to remove it entirely, so the last two bits of the puzzle were detaching the electrical connections to the 12V and Aux outlets, and then getting it over the shifter.





Aux connector is green, 12V connector is black.

The 12V is a compression fit, and the Aux has a clip on the backside you have to depress.

I had my car in Park to start, but it has to be in Neutral to get the console over it. To move the shifter without turning on the engine, you stick your key in the slot on the side of the shifting mechanism (circled in the photo).





Stick your key in the slot where the red circle is to move the shifter.<br/><br/>The yellow X shows a similar gasket type thing as is on the O2 sensor, but this isn't where you want to go.

Now you can take the console cover off and find where the wires go. You'll see a gasket and wire to the rear of the shifter, but if you look at the wires, you can see that they're different than what's on your part, so that's not what you're looking for. The good stuff is under a pad of foam to the front side of the shifter.




Here's a closer look, with some of the foam still in place. You can see the white wire. It's an awkward spot to get into.



Here's the best shot I could get with everything in situ. The red circle shows the clip where you have to connect the wires. The green circle shows the port through which the wire goes. The O2 sensor can fit through this hole.

So in my case, the gasket wasn't fit in place properly, which may have had something to do with why it was failing (see the pictures of the part further down). But seeing that, and the wire clip, I knew this is what I was looking for. I unclipped it, and dropped it through the hole.

I think at this point I jacked up the passenger side of the car, put it on an axle stand and chocked the rear wheels. Then I started trying to get the sensor out. I think it's supposed to be easy, especially with the socket I bought, but the sensor was either overtorqued or there was corrosion in there, because I couldn't get it to go with my 3/8" socket wrench. The socket I got also had a 1" hex head on the back, though, so I was able to use my 27mm (a little big, but it's what I have on hand) combination wrench on the socket to get a greater mechanical advantage. I had applied a little heat to it, too. This got it loose, and then I was able to compare the parts.




New on top, old on bottom. They look similar enough to me.



The old one clearly shows some abrading of the insulation. The wires were dangling a bit when it was installed, so having the gasket fitted improperly may have allowed too much play in that?

I don't know if the sensor was too baked, but I am pretty certain the condition of the wires would be a cause for malfunction, too. As an aside, both of the parts were branded NTK, so I feel pretty confident that although this part isn't Honda, it's what Honda uses.

So at this point, I applied some of the anti-seize (because I didn't like how the previous part seized), and put it in. Attaching the wiring clips was a little challenging, but I found one finger and a screwdriver were able to navigate the confined space well enough to get the sensor attached.

Then it was a matter of putting things back, which went well. I had disconnected the battery, which erased the code, but I have been driving my car pretty much daily since then and the code hasn't reappeared (and I have a clean emissions test in hand now, too).

All in all, it seems to have done the trick, not costed as much as taking it to the dealership and only taken one Saturday morning (probably a little less if the part hadn't have been seized and if I knew where to find the wire connectors first).