does the ECM store codes until cleared with the HD "Digital Technician" tool? I've been getting a P0152 code intermittently. I cleared the last code using the speedometer diagnostics. No other codes were present. So even though I cleared the code, is it still stored in the ECM? And will remain there until cleared with the digital technician tool or have I erased it totally. Check engine light was not illuminated along with this code.

 

Don't quote me on this but I think the ECM will store a 'Historic Code' for 50 ignition cycles and if the code doesn't reappear in those 50 cycles then it's gone... I think!!

 

I believe that is correct, Oz.

 

If a code reappears after I've cleared it via speedo diagnostics, is it logged in the ECM again with a date stamp, for instance, over a period of 3 weeks I get this P0152 8 times, and every time I clear it via speedo diagnostics, will an HD tech with his "Diagnostic Technician" see a data log of the multiple failures? Sorry if the questions seem rather dumb. I'm new to this fuel injection stuff. It is a steep learning curve for an old guy!

 

The digital tech does not keep a log of how many times it was set and cleared. It just sees if the code is active and any historic codes.

That code is for the rear O2 sensor having high voltage. Do you have mods or was it mapped? Unless it has a problem with mods or mapping, it's most likely a failed sensor or wiring problem.

 

Thanks Ed, I knew what the code was I just wasn't sure about the capabilities of the ECM. I check the diagnostics after every ride, sometimes there's nothing, once in a while the P0152 is present. I'm having an intermittent problem with the bike dying at idle, idling too low then eventually dies. I've checked the IAC, cleaned it, and I can see it functioning actuating the stop/run switch. New stock air filter. This bike, was a new to me '07 Ultra, got it last summer. Have had the problem since I've had it. Only mods that I'm aware of, I put on a set of pipes this last winter. At this point I don't know if the ECM has been remapped or not. I'm leaning toward an intermittent failure of the rear O2 sensor. Don't know if that would have any bearing on the dying at idle issue.

 

It certainly would not be the first rear O2 sensor of that vintage that failed. You could swap the sensors and see if the code follows, but for the possibility of the threads staying in the pipe and the time involved, I would just simply replace the rear O2. You might want to pick up an M18 x 1.5 tap. Any time you remove the sensors for the first time or before you install a new pipe you will want to chase the threads to prevent future grief.

 

Thanks for that tip. Sounds like more tools, a guy can never have too many! We'll see what happens.