Bafang BBS02 750w errors 21 and 4

[laudou]

Hi
I just received an e-bike with a Bafang BBS02 750w pre-installed. After assembling it, I took a short ride test. After about 400 meters working OK, a red alert appeared on the DPC 18 display:"Speed sensor problem" Then I lost all power assist. Back home, I checked the error codes: 21 and 04. I know that error 21 is related to the speed sensor. At first, the speed sensor led was always on, even when the wheel was not spinning. What caused that problem? As for error 4 throttle related. I unplugged and replugged the throttle cable but the 04 error did not go away.
Any suggestion would be greatly appreciated.

 

[Gionnirocket]

Error 21 is usually because the spoke magnet is missing or is not properly aligned. The LED on the sensor should blink as the magnet passes by the sensor. Check your spoke magnet.
04 error could be that the controller Throttle Start Voltage is not set properly. Possibly set too low.
Could also be a faulty throttle.... What happens if you leave it unplugged?

 

[laudou]

Error 21 is usually because the spoke magnet is missing or is not properly aligned. The LED on the sensor should blink as the magnet passes by the sensor. Check your spoke magnet.
04 error could be that the controller Throttle Start Voltage is not set properly. Possibly set too low.
Could also be a faulty throttle.... What happens if you leave it unplugged?

View attachment 150413

Hi
I'll double check the speed sensor. As for the throttle I cannot check if the error 4 will go away when I ride the bike since I am getting no assistance at all.
Thanks