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Error code 21, Odometer say's 4 million miles, HELP

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    Error code 21, Odometer say's 4 million miles, HELP

    Bought a brand new Z1 with Bafang Ultra M620 motor. All display functions are working normal. My mph is accurate, my trip odometer is working and I can go into settings and reset it. My wheel size is correct.
    I've only had the bike for less than a week. The odometer was working perfectly and I was probably up to only 40 or 50 miles. Then I noticed the odometer for total miles is now reading 4,200,000 something??????
    Under error codes on the display I got a reading of error code 21.
    I have read that this has to do with the speed sensor.
    The speed sensor was in fact slightly off and I used the security torx bit to loosen the magnet and properly adjusted so it passes perfectly across the speed sensor.

    I turned the display off and back on again.

    I removed the battery and then put it back on.

    I reset the trip odometer multiple times.

    Everything seems to be working perfect except my bike says it has over 4 million miles on it!!

    This is extremely frustrating as the bike is only a week old have not contacted Luna officially yet on this as it is the weekend.

    The only thing I would like to add is that I did purchase the mini 48 volt charger from Luna that has a toggle switch allowing you to only charge the battery to either 80%, 90%, or 100%.

    I charged the battery with the mini charger last night for the first time setting the toggle switch to 80%.

    When the charger turned off I turned the bike on and it said that it was only 70 percent charged.

    Not sure if the calibration on my mini charger has a problem or not?

    Regardless I then switch to toggle switch on the mini charger to 100% and continued charging.
    The charger again turned off indicating it reached 100% as the toggle switch was set to.

    But when I turn the display of my Z1 bike on it said it was only about 90% charged?

    This led me to believe that perhaps my charger was defective I am not sure why the toggle switch does not seem to be working?

    Has anyone got an error code 21 but the speed and trip odometer are all working normally the only problem is the bikes total mileage odometer is out of whack what could be going on here?

    Is there any way to reset the odometer?

    I appreciate any help from The forum members and or luna staff who may be monitoring.


    Seems like someone else had a similar issue with a zillion miles popping up. I don't recall if that was a Bafang or not and I don't remember that there was ever a reply with a resolution.

    On the percentage thing these are pretty well known to not be accurate. Many displays will let you change that to voltage and that is what a lot of us prefer because it seems to be much more accurate. There are charts online that show you the volts vs percent if you want to relate a percent to the voltage.


      Thank you !! : ).

      I have been reading about the voltage versus percentage readout opinions.

      I definitely will try to develop a feel for voltage and change that on my display eventually.

      If anyone has an idea of why my odometer suddenly says it has 4 million miles on it and has an idea as to how to fix this I would greatly appreciate it.

      Thanks in advance.


        Seems to be a definite issue… :-(

        Is it possible to reset the Odometer? I got one in from Luna this month and notice the Odometer has over 42 million miles showing. I only see about resetting the trip.

        Hope Luna has a better response for you.

        See my completed Magic Pie V5 rear hub motor E-Bike build HERE.


          Thank you T.C.


            Are you talking about the trip odometer or main odometer?
            FYI: You are supposed to charge to 100% for the first 5 or 6 charges with a new battery.


              I am talking about the main odometer. It started reading 4 Million plus miles a few days after receiving my new bike.

              It reads exactly...

              4 294967 mile
              The trip odometer works fine and I can go into settings and set that back to zero after every ride.

              The speed is accurate also no issues there.

              Another forum member left me a link where two other individuals had the same problem and interestingly the dates of their posts were 5/31/22 and 6/13/22.

              There seems to be no answers as to why the odometer reading for total mileage suddenly goes to that large number?

              One of the other posters posted a picture of his odometer reading and interestingly enough our numbers are identical except that he has two extra digits at the end of his number.

              I'm not sure what to make of this but it's certainly annoying considering the bike is brand new and less than a week old.

              I plan on contacting Luna after this weekend too try to get a fix or explanationon this.

              I will charge the battery to full capacity for the next few times.

              Thank you.


              • TornadoDodger
                TornadoDodger commented
                Editing a comment
                Ever find a solution? My DPC-18 display started having this same exact problem a week ago (build is only a month old...) I did contact my supplier to find out if they know anything. It's funny because even the number 4294967 is the same- which makes me think it's some sort of error code internal to Bafang and they should know what it means.

              I was wondering, although the BBS that I have is a totally different beast with a 750C display, the menu has an option to reset to factory defaults. This zeroed out my main odometer.
              is it still tracking miles over the 4mil+ or just stuck at that number? If Luna says nothing can be done, I would be inclined to believe is their product.