Quick answer
The motor runs roughly, jerks or judders. Most likely cause: a damaged motor cable or a loose or wet motor connector. Try this first: turn it off and on again.
Code meanings vary by brand. The same number can mean different things on different displays and controllers. Check your bike's manual to confirm.
About the Bafang DPC-10
When an error is detected, a wrench icon appears and a two-digit code shows on the screen. source Bafang's manual says: when you see a code, restart the system first. If the problem isn't solved, contact your dealer. source The DPC-10 keeps your last ten error codes. Press i twice quickly to open the menu, then step through it to "E00". "00" means no error. source This list is for the CAN version (DP C10.CAN), the one Bafang publishes a manual for. If your DPC-10 is a UART version from a kit, its codes may be different. Careful: some numbers mean different things on the Bafang DPC-18. source
In plain English
A hub motor needs all of its power wires and position sensors working to run smoothly. If one is damaged or loose, often at the axle or the motor connector, the motor judders, especially when starting from a stop. It may make a grinding noise even though nothing mechanical is wrong. Loose battery connections can cause a similar pulsing feeling.
Step-by-step checklist
Reset
Work from the top. Steps go from free and easy to shop jobs. Switch the bike off before touching any connector. Tick each step as you go. Your progress is saved on this device.
As an Amazon Associate I earn from qualifying purchases. Steps marked "affiliate link" link to Amazon.
1 Turn it off and on again Free Switch the display off, wait 30 seconds, then switch it back on. If the code clears, note what you were doing when it appeared, in case it comes back.
2 Look over the motor cable Free Follow the cable from the motor along the frame. On hub motors, look closely where it leaves the axle: it often gets pinched when the wheel is removed or crushed when the bike falls. Look for cuts, kinks or bare wire.
3 Reseat the battery Free Switch off and slide or lift the battery out of its mount. Wipe any dirt off the metal contacts on the battery and the mount, then put it back until it clicks and locks.
4 Unplug and check the motor connector Easy Switch off and remove the battery. Follow the motor cable to its plug (often near the rear axle or under the frame). Pull it apart, look for bent or pushed-back pins, water, corrosion or burn marks. Burn marks mean stop and see a shop. Clean corrosion with electrical contact cleaner and let it dry fully, then push it back together firmly.
Need it? Electrical contact cleaner spray on Amazon (affiliate link)
5 Wiggle-test the wiring (motor off) Easy Switch the display on, but don't run the motor. Gently wiggle each small connector and cable one at a time, by the handlebar and along the frame, and watch the display. If it flickers, resets or shows a code, you've found the loose spot. Switch off and remove the battery before you reseat it. Never wiggle wires while the wheel is spinning, and leave the thick motor and battery plugs to a shop.
6 Dry the bike out if it got wet Moderate If the problem started after rain or washing, remove the battery and leave the bike somewhere warm and dry for 24 to 48 hours, then test again. Don't use a heat gun or put the bike next to a heater.
7 Have the motor tested Shop job If the cable and connector look fine, a shop can test the motor's wiring and sensors. Opening a motor or working on its high-current wires is a shop job.
⚠ When to stop and get a shop
Stop and see a shop if you see melted plastic, burn marks or a burning smell at any connector, or if the motor gets very hot. The thick motor wires carry high current. Don't cut, splice or bypass them yourself.
Anything inside the battery, the controller, or the thick high-power motor wires is a job for a qualified e-bike shop.
Parts you might need
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Only buy a part if the free steps didn't fix it. Always match the voltage and connector type to your bike.
Electrical contact cleaner spray Cleans dirt and corrosion from connector pins and battery contacts.
View on Amazon Dielectric grease A thin coat on connector seals helps keep water out after you clean them.
View on Amazon Motor extension cable Replaces a damaged section of motor cable. Must match your connector and pin count.
Match your bike's model first. Ask a shop if unsure.
Still not fixed?
Pages to try next:
When it's time for a shop: if you've worked through every step and the problem is still there, take the bike to an e-bike shop. Bring your notes on when it happens, plus the code.