Went on a 100 mile round trip ride the other night and during the last 10 miles the check engine light come on on my wife's 2008 street bob EFI. Did a manual diag check and the ECM returned code P0131 Front Oxygen Sensor Low.

Details:
Bought the bike stock/used last summer with 2500k miles. This spring changed stock exhaust to Vance and Hines straight shots without adding any fuel management or remapping. Had a candid conversation with a HD mechanic and he suggested if you are just wanting the sound and not worried to much about performance than fuel management was not needed.


During the replacement of the pipes the front 02 sensor was seized in the stock pipes and while trying to remove it I stripped the threads, so I replaced it with a new 02 sensor from HD dealer when installing the v&H straight shots. Installation went smooth and there were no noticeable performance issues with the new exhaust (300 miles) until about 1 week ago when my wife tells me after her ride that mike bike is making popping sounds....ok...so I took it for a test ride. Sure enough after each gear change and upon giving it throttle the bike popped or backfired, didn’t do it every time, maybe 70%, it was more noticeable when you would be more aggressive with the throttle. First thing I thought was that I probably do need some type of fuel management...damn...to good to be true not to have saved $500...


Also, last night during the trip home I noticed blue flames about 3 inched from the end of her pipes, other than looking cool I thought the bike must be running rich...But when it threw the p0131 code and I did some research I see some are saying the low code is interpreted as running lean...???? I guess meaning running lean on oxygen on high on fuel (what I would call rich). Regardless....


Seeing that I went from stock to aftermarket exhaust with OUT making any changes to fuel management it seems logical that something needs to be done with the fuel/air mixture...Does it sound like I’m on the right track???


If so, and given the abundance of fuel management options out there...what is the best choice for the money??????

 

I would definetely look into getting a fuel management deviceon that bike. They run lean from the factory and putting pipes on it made it a bit leaner. Will it kill it? Probably not. But it will run better and probably last a bit longer f tuned correctly. Personally I run a power commander and while I have no complaints about it, I am not sure if it is the best choice regarding easy to use/program. There are many choices out there, I'll leave it at that.
As far as your "current" lean issue with excessive back-firing; I would be willing to bet that one of the pipes has worked its way loose from the head. Check the flange bolts and make sure the nuts are still tight, and any other fasteners on the pipes where there is a seam. For the bike to suddenly develop a problem like this usually mean that something is wrong.

 

Well I found the source of the exhaust leak...There was a crack in the pipe just above the o2 sensor on the front pipe. this would explain the error code P0131!!!

Now my question is do you all think this is a defect in the pipe or caused by stress in the pipe from improper installation? Note* I followed manufacture installation guide and HD torque recommendations and I cant really see where I would have place undue stress on the pipes...but...I'm not a professional Bike mechanic so I guess I could have

I've contacted the online company I purchased the pipes from to see what can be done. Gut feeling is I'll be buying a replacement part from V&H but maybe I'll get lucky...

I've attached a picture...What do you think?

 

couldn't open the last image...maybe this one will work....

 

bump to the top

 

You can have that one welded. However, my first call would be to V&H to ask them about it. They are a good company, anytime I have ever called them, they have tried to help me out.
I would not demand a complete set of pipes, but I would try to get them to offer a part replacement. Be nice, tell them how much you love thier product, you know they are top shelve pipes, and just confused about why it happened.

 

Thanks tlb! Do you think the bike will suffer any long term effects if I continue to ride it until the replacement part comes in???

 

You could float a value or burn a piston. You are not getting good back pressure. Just take it off, run it to a muffler shop they should be able to weld it for $25.