Rear 02 sensor error

[Beebop]

Hi guys.
'06 XB9SX, 80000km.
On my way home last night , and again on my way to work this morning, the CEL came on for
about 5 km, then went off. Bueltooth showed a stored rear 02 sensor error. Is this likely
a component failure in process, or should I be looking at a possible wiring issue ?
Thanks.

 

[Barrett]

Hi guys.
'06 XB9SX, 80000km.
On my way home last night , and again on my way to work this morning, the CEL came on for
about 5 km, then went off. Bueltooth showed a stored rear 02 sensor error. Is this likely
a component failure in process, or should I be looking at a possible wiring issue ?
Thanks.

Is this likely
a component failure in process

Possible...but not always.

The ECM is seeing sensor values it doesn't like....hence the intermittent CEL.
1-Wildly fluctuating engine temp signal being sent to ECM can cause this. Check ETS connector for condition and ETS harness for chafing. Historically, a known problem.
2-Ground is being interrupted somewhere. Check them all and in particular, the ECM grounds.
3-You FAILED to mention rideability issues, or lack thereof. If active CEL immediately preceded by cooling fan activation...it is always a failed ECM ground.
4-This condition is typically NOT a failing O2 sensor or intake seals. NO mention of AFV value during this horrific experience. TPS reset 10% of the time will resolve this. Worth mentioning.

 

[Beebop]

Thanks Barrett.
If I didnt see the CEL , I wouldnt have known it happened, so no performance issues of any sort.
My AFV has always been within 10% of 100, but I did not check that specifically, will do so if
it happens again. I did have the ground under the seat off earlier this week, I will check if that
maybe is an issue.
Cheers

 

[Beebop]

Well I didnt get a chance to check yesterday, but the trip home gave no CEL.
Hopefully the weekend will give me more time.

 

[Beebop]

ok so this morning I made some time to look at it.
Pulled the entire airbox, checked cables for chafing , reseated everything
I could access. Added a ground to the rear coilpack mount.
Hooked up the Buelltooth and this is the readings.
Oh and while I was at it, I did a TPS reset.

 

[Cooter]

All I can see is that the AFV reading is telling the ECM to pull almost 20%(!!) of fuel from the entire map. An old or lazy O2 sensor can cause that (but that is a guess, not a diagnosis). You can check O2 running voltages under live data.

The bike will run better if you re-set AFV to 100 and set the AFV limits to 90-110. Its not a "fix" though.

If it's cheap enough for you to guess, the O2 is behind the cooling fan. Hang the rear of the bike, take off the seat, rear shock, and fan (the bottom slides towards you first and then out the bottom). It is possible to slip a 7/8" wrench under the frame to remove the O2, but a dedicated socket or crowsfoot on an extension is easier.

 

[Beebop]

Well the only thing I've noticed is a slight exhaust blow between the headers and the pipe. I'll tackle that the weekend and
reset the AVF to 100 and see where it ends up. I can swing a spanner, but when it come to tuning and electronic brains, I
get into deep waters. I appreciate everyone's assistance and patience.
I do have my wife's 05 model which I can swap parts with if I need to , but access to the sensor makes that option
lower down the list of things I want to do.
Cheers

 

[Beebop]

And just to post a follow up, The bike was unused for a month or so while I hacked the pipe and made
it into a Buell race pipe replica, and also did some cosmetic work. I fixed the slight blow it had where the headers
meet the main exhaust, double checked the grounds, check for chaffing etc, and have been using it for a
few weeks to commute. It runs great , sounds great and I have had no issues.....well until yesterday.
My son, I and a few friends went for a quick 200km breakfast run.
The outbound trip was uneventful. On the return, I decided to open it up a bit and get rid of the cobwebs. Just as the
needle hit 200kmph, the CEL came on and the engine lost some power. I eased it off till about 140, and then the CEL
cleared and it ran fine. The remainder of the way home, as soon as I exceeded around 4500rpm (140kmph), the CEL would
come on with a loss of power. The power loss doesnt always happen with the CEL coming on though.
I rode home at a sedate 130, and immediately connected the Buelltooth.
My AFR was a very acceptable 96,2, and there were 13 incidents of rear 02 inactive. This is currently my only
mode of transport, so I used it again to work this morning , and I had one occasion where the CEL came on, but no
performance issues.
So I'm at the stage where the sensor is looking like the place to start with a replacement.
Are there any basic tests which can be done on it, or do I just replace and see what it does ?
Also are there any alternatives available ?
Thanks again for the valuable support offered here.

 

[Cooter]

It's showing like there's a problem in the O2 circuit. Not necessarily a bad sensor, but the ECM thinks theres something wrong in the circuit.

It's acting like the fuel system is weak, clogged, or the internal hose has pinholes in it.

 

[cvc]

Verify no leaks on you exhaust and the GM single wire sensor is under $20 throw one in then check your live data warmed up with the seat off do a wiggle test on the harness and pay close attention to any spikes in O2 data. I have several B bodies and keep a sensor on the shelf that fits them and my Buells the box is getting old they last so long but still cheap insurance to put in a new one first.

Then follow Shaughn’s advice and check fuel delivery. That is more time consuming and if you get lucky the sensor will fix it.

 

[Beebop]

Well to update with current status.
A few days after I last posted, as my clocks rolled over to 80000km, my speedo and odo stopped
working. I followed google and removed the sensor. It had very little grey matter, but I cleaned
it up, replaced it, and also cleaned and reseated the 3 pin connector.
Since that day I have had a working speedo/odo and also never seen an O2 error again....

Then yesterday on my way home, I had a brief engine stumble along with the CEL come on
for about 2-3 seconds and then all returned to normal.
A quick check when I got home showed no error stored and an AFR of 95,6 .
All other tests passed and nothing "seems" out of place.
So my question would be, is this then a sign of a failing fuel pump, or
should I be looking elsewhere. ?
I could run live data on the Buelltooth, but I honestly wouldnt know
what to be looking for.

 

[34nineteen]

Well to update with current status.
A few days after I last posted, as my clocks rolled over to 80000km, my speedo and odo stopped
working. I followed google and removed the sensor. It had very little grey matter, but I cleaned
it up, replaced it, and also cleaned and reseated the 3 pin connector.
Since that day I have had a working speedo/odo and also never seen an O2 error again....

Which sensor?

 

[Cooter]

I think he means O2 sensor.

One small stumble and no clue to why means ignore it, or the depth of that wormhole knows no end. You can LOOK for things though. Wash it, wax it, look at what you're doing. Its a good way to see your own bike up close while doing the Lords work. Even take the airbox off and LOOK closely at everything. Your AFV is fine 90-110.

 

[Beebop]

Sorry wasnt clear.
the speed sensor was removed and cleaned.
I have not yet touched the O2 due to its location
and basic lack of time on my side.

 

[Beebop]

Well its been a while, and honestly no progress on this.
After not finding anything obvious, I bought a new O2 sensor
yesterday and fitted it. When for a run today, and exactly the same symptoms.
Constant speed above 120kmph for a few km's and the light comes
on again. I usually drop speed down to 100 or so when this happens.
The CEL stays on for 3 or 4 minutes and goes off again.
The bike runs so well its hard to imagine there is anything
else wrong or failing. I really need to fix this as I have a potential buyer, and
I wont sell it in this condition. It has to be right. If I had a fuelling issue
I would expect to see a Lean or Rich error, but its always inactive.
Could another sensor such as Temp be causing the ECM to kick out
this error ?
All suggestions welcome.

 

[Beebop]

Well my own question was answered yesterday when my fuel pump kicked the bucket.
I managed to nurse it home spitting and farting, dying at every opportunity.
Hopefully the replacement will be the end of my problems.

 

[Cooter]

Go OE or PM Barrett for quality fuel pumps and re-build kits.

Do NOT get the cheap stuff off e-bay. It is wrong.

 

[kz6fittycent]

I can attest to Rev-Mo's pumps (Walbro): https://www.rev-mo.com/fuel

And I'm pretty sure others can speak to Aagaard's: https://aagaardmotofoundry.bigcartel.com/product/stark-fuel-pump-kits-for-03-09-buell-xb-motorcycles

This is just in case Barrett is out...he probably ain't, but you know, just in case.

 

[Beebop]

Well despite my fuel pump biting the dust, the replacement thereof and also replacement of the
filter while I was in there, was a short lived reprieve. I got to the stage where the bike stood and I was using
my R1200RS exclusively. Not ideal as commuting is not what I bought it for.

So to date this rabbit hole has cost me:
1 x 02 sensor
1 x fuel pump
1 x fuel filter.
2 x plugs

Still getting Rear 02 sensor inactive error code, and poor performance.
This week I decided to test my patience a bit more, so I pulled apart and
tested all wiring and connectors with a meter, and cleaned out each connector with
cleaner. Also took apart all the ground points, cleaned them up with fine sand paper
and electrical cleaner.
Took it for a run, and this time it came back with 2 extra codes:
Temp sensor short to ground
Fuel pump short to ground

I put all my collective brain cells together and came up with...... nothing..
I have always figured this to be a fueling rather than electrical issue, so
I did what any self respecting husband would. I swapped out my fuel pump assembly
with my wife's. She has the '05, mine is an '06.
And would you believe it, problem resolved.
Done just over 100km's so far and not so much as a miss or cough.
So I have a new fuel pressure regulator on its way for my wife's bike.
(She can have all the new parts).
This should conclude this season of "dealing with a frustrated Buell owner".
I can now close this thread as "resolved".
Thanks for everyone's input, I thought I'd just post this incase someone
ever deals with a similar set of symptoms, and doesnt want to lose as much precious hair
as I have.

 

[Cooter]

I'm glad you got lucky.:up: