On my 2007 Ultra Classic (15K miles) I am getting a code that the rear sensor is reading high. Before I just replace the sensor what (and how to) tests should I perform on the sensor/circuit? I have a shop manual. Looking for someone here who has had this problem. I am sure of the code meaning. I just do not have the actual code value memorized as I am writing this.


I have a Fuelpak installed and adjusted for the monster ovals slip-ons and K&N filter. All codes are per spec. Do I really need this fuelpak device with so few mods? (separate question but may relate to the error code?)


This bike is faily new to me. I bought it last year with 5300 miles on it and put about 10K on it so far. I replaced the spark plugs earlier this year.


Thank you for your time.

 

I leave it to others to advise you on the need for the fuel pak, but from what you describe -you should be able to safely remove it as a test to see if you still get the code riding without it.

 

sensors can go bad- esp if subjected to silicone.

try swapping the sensors and see if the problem follows the sensor or stays at the rear cyl.

remove and re-seat the tuner connections ( or try running without to test).

the o2 sensor should normally output .45 volts DC with a stoich mixture.

less voltage means a lean mixture, high voltage means a rich mixture.

so if could be a fault in the tuner or settings--- maybe just too rich



plugs: did you use stock type or are they "magic plugs" that make promises in the pages of magazines? stock plugs and wires often work best with the HD ignition system.
a misfire could give a high o2 sensor reading.


what we need to determine is whether the o2 sensor is giving spurious readings- or if it is correctly indicating something wrong.




many of us use nightrider.com xieds- they are an inexpensive uncomplicated resistor pack which plugs inline with the o2 sensors- they lower the voltage from the o2 sensor to the ecm - so the ecm makes the mixture about 8% richer.
That's what i use on my 09 96" with hi flow intake and exhaust.

a possible bugaboo with add-on or piggyback tuners is the extra connections may cause problems- the voltages and amperes of the sensor signals are quite low and any resistance in the connections can confuse the ecm


mike

 

I had not thought about swapping them, just figured they would be different. Good idea. For starters I removed the fuelpak so we'll see if the code comes back.


Thank you for taking the time to help me.

 

I took a ride after removing the fuelpak and the codes are back. Bike runs fine.


1. In swapping the sensors to see if the problem follows the sensor to the front cylinder, what is needed for seals, gaskets, etc.? Or, do they just unscrew and screw back in? Do I coat the threads with anything?


2. What if I do nothing and just let it run as-is? Will damage result? Besides a little pinging when accelerating hard from lower RPMs say around 2000 will there be anything getting damaged by just riding it.


Thank you

 

pinging will kill a motor, don't let it happen

unfortunately you can't plug a snap on obd2 scan tool into a HD bike

easiest thing is to pull the tuner (you did) then see if it is still there.

you have the code with the stock ecm , so absent of a easier way to do this, swap the front and rear and see if the problem migrates after you clear the codes.

if migrated replace sensor, if not check connections (ecm harness, o2 harness, injectors) fr proper function/connectivity.

good luck

 

Don't the front and rear O2 sensers have different plugs on them?? for some reason I remember that they do so that the wires don't get reversed...I could be wrong here...

 

My manual says to reinstall with a new seal washer. Are those special crush washers? Where would I get them? Are they a dealer-only part or pretty common? I assume that I can reuse them for the purpose of this experiment.


If I have to replace the sensor is there an aftermarket option or is that a dealer-only item because they are unique to HD?


I mentioned I replaced the spark plugs and someone asked about what I replaced them with. I went to NAPA and got the Champion equivalent. 2-bucks each. Work fine.


as always, thank you for your help.

 

Regarding the plugs. The guy who dyno tuned my bike changed out my plugs with standard Harley plugs as part of the dyno. It had champions in it. He told me from his experience to only ever run Harley plugs. For whatever the difference is in price, I'll take his advice.

 

i've got 2 o2 sensors from a 2007 roadking that i pulled to install a pciii. i don't need them, so if you want them, they're yours for the cost of postage.