O2 Sensors Crossed????

[N456SK]

Installing new exhaust on a used 2012 Limited I bought, noticed the rear O2 sensor had a light gray plug, remember reading that black connector went to back, so I just figured someone else got it wrong. I had my brothers 2010 EG setting in shop, I put a new pipe on it when it was new, remember specifically marking the sensors, went and looked at it and it also had light gray O2 sensor hooked to rear, so checked in service manual on wiring diagram by wire color and it's showing the black one to go to back cylinder! So what is correct, could factory screwed up? Which is right? Help!
Steve

[Coyote]

Black is back..

[rigidthumper]

I've had brand new bikes from the crate with 02s hooked up backwards, so yes, it does happen. Hell, I've seen SE cams in new stock bikes (CVO cams in a fatboy slim) as well as 2 different colored side covers, I remember one softail with a red back fender and a black front fender and gas tank.  Stuff happens.

[rbabos]

deleted.

[hrdtail78]

I have seen it once.  It was easier to depin and repin, over twisting wires or removing exhaust.

[Jamie Long]

The factory head pipes are also marked with the letters B (rear) or G (front) which is cast next to the appropriate sensor boss. 

[wavlovr1]

I've seen several O2 sensors in backwards...

[TXP]

Part of this confusion is due to if you look at the connectors the black one is in front, but it is for the rear cylinder.

[a2wheeler]

I'm in the process of changing out my pipes also - 2010 Ultra. I see that the front sensor is plugged into the correct front plug, but the front sensor has the black wire and the rear has the gray. I see the front sensor part # is 27729-10 and the rear is 27809-10. What is different about those sensors - I expect not just the wire colors, one shorter than the other? Looks like I should install them in the proper place on new pipes.

[joe_lyons]

Dont worry about the plug location orientation but that the black plug is always in the rear cyl pipe.  All else will be fine if you always remember that (Black is back)

[FSG]

Black is back   =//=   Back in Black 

AC/DC - Back in Black

[a2wheeler]

I'm a bit confused with your comments Joe.  My bike ran fine with the current location of the sensors. The plugs are the connectors from the ECM to the sensors. Currently the ecm is plugged into the correct physically located sensors. The problem is that the sensor with the black wire is in the front cylinder location. My question is - what is different about the two sensors to make any difference. Bike runs fine. If the ecm thought it was controlling the front cylinder but getting feedback from the rear cylinder , I can see how that would be a problem.

[joe_lyons]

Most that I have seen that had the sensors switched did not run the best. Yes the sensors are color coded for front and rear because the ecm controls the front and rear separately.  You may possibly have one that had the front and rear plugs from the wiring harness wired backwards but I havent seen that before.

Thank you FSG that will give me another reason the listen to AC/DC

[a2wheeler]

Ok, thanks. I think I have it figured out. From the wire diagram the sensor with the black wire should be attached to the black plug, which can only plug into the what the ECM thinks is the rear cylinder. The sensor with the grey wire is attached to the white plug for the front cyl.  In my case the sensor with black wire is connected to the white plug, but that sensor is in the correct bung for the front cyl.  I would think that not too many of the sensors get the wrong colored plug installed from the factory. But it appears more common that the sensors are installed into the wrong bung.  It may very will be that is what happened to my bike from the factory (sensors in wrong bung holes) but someone at the dealer 'fixed' the poor running by repinning the the wires so the plugs were reversed. Problem is solved on my bike, but it looks weird. I suppose I could repin back to where it should be - black wire to black plug. I'm reinstalling the sensors, so I will get them in the correct place. I have not pulled them yet, so I don't know what condition they are in. 20K miles on the bike. 

[cardboard]

Why Didn't harley make it so you  could swap the plugs instead of having to pull the 02 sensors and reinstall them & the pipes.
And Which sensors is on the front of a stainless steel Jackpot exhaust . The front to back of the pipe. This is the 12mm Lambda sensors
Think I'm gonna have to pull one and sit down and look at it.

[joe_lyons]

Black is back.  You can just swap the plugs if they are backwards. You just have to use a knife and shave off the index tab