99,000 miles, first code

Another quick update. I went under and everything looks OK, except for a little tranny fluid on the connector... I had a leak in the nearby trans cooling hard lines that I fixed last week. The connector is just a little wet. They are supposed to be sealed but, who knows, maybe a little trans fluid got in there? I dunno. I wiggled the connector then ran the truck again and the B1S2 sensor is responding now so I guess the sensing element itself is OK. I need to run to the parts store and get some electrical contact cleaner, pop the plug and give it a good spray.

 

I had a P0420. Swapped sensors to no avail. Side to side, not replaced. I eventually found a tiny soot mark where bank 1 cat connects to the Y pipe.

I used a Bluetooth OBD scanner and torque. Created a graph gauge for each of the sensors and bank 1 was all over the place like a coked out spaz.

I would absolutely be looking for a leak first

Wire lengths are different on the V6 O2 sensors. I noticed when I swapped mine side to side.

always swap when you can, rather than throw money at it.... Like throwing darts with a blindfold on. In the dark.



I'll add that all 4 sensors and the cats are original on my truck. I doubt it's the sensors.

 

Logging the data further it looks like B1S2 is still faulty. It responds sometimes but not even close to being in synch with B2S2, and then goes dormant here and there. A broken catalyst or a leak should create a constant problem, not intermittent. So at this point I am going to replace the sensor. It's only money, they make it every day. ;-) It could still be something off with a B1 injector but that seems more unlikely than a failing sensor and the truck is running smooth. I also just replaced the spark plugs and they were all clean and in great shape, Densos with 31,000 miles or so on them. Gaps were only a couple thousandths over.

 

hey just an afterthought, i'm not big on adding additives too my vehicles but my Honda fit had a very similar issues @ 45kmiles i went into autozone had the code run came up with an 02 sensor. The ASE tech there recommended Cataclean before i go replacing my 02 sensors, the code came back after i added it but followed the directions and havent had an issue in 20k miles. Just my 2 cents i thought it was snake oil but it worked for me.

 

I'm not big on additives myself but I may try this. I installed the new sensor and it is a lot better. The S1B2 and S2B2 data traces are almost identical... except for once in awhile the new sensor holds a mostly steady higher voltage than the other bank for a "while", then resumes tracking almost identically. This happens mostly when easing up on the throttle, but not all the way to idle. When it is acting up it will hold a mostly steady voltage that is higher than the other bank... then will resume tracking and mirroring the other one after some time, like 15-30 seconds. And it doesn't happen every time I ease off the gas. What this is telling me is that when this happens that side stays a little richer then the other. In any case, it is a lot better than it was, but there may be something going on with an injector sticking open a bit and maybe over time that damaged the original sensor? Or maybe there is a very small crack in the media in that cat? Bottom line is truck is running great and I have no codes so all is good. I may throw a couple bottles of Techron at it and log the data again.

Does anyone have a handy app that will graph text csv data? I am not sure I can figure out how to make Excel do that.

 

So I definitely did NOT see this behavior on the 8 mile drive with the new sensor, while the old one would zero out for periods of time. So I am hopeful it is fixed...


" P0137 means the O2 oxygen sensor's voltage remained low for longer than2 minutes. This, is interpreted by the ECM as a low voltage condition and sets the MIL. Bank1 Sensor 2 is located to the rear of the catalytic c…"

 

Thought some of you might be interested in this... After I swapped the B1S2 sensor I did a data logging run and made the graph below in Excel. At this point this is an academic exercise since the truck is running great and there are no pending or locked in codes. The chart shows upstream and downstream O2 sensor voltages for both banks. There are a few times when the downstreams depart a bit from each other, with the B1S2 (gray line) running a tad higher voltage than the B2S2... but both upstream sensors track almost identically. So that tells me (I believe) that the bank 1 cat may be losing just a bit of effectiveness... or maybe has a little crack that allows a little bypass now and then. In any case none of this is code worthy, at least for now. Unfortunately I didn't do a run like this before I replaced the sensor.