Carrera error code 21

[Macca99]

Hi. Just joined here. I have been using and building ebikes for 10 years just for personal use. Recently bought a second hand Carrera Crossfire, on the cheap, because the owner could not get rid of the error code 21. I searched forums and tried all the tricks but could not get rid of it. Finally, I took a spare control unit I had in the shed and just connected the battery, the motor and a thumb throttle and and it all works perfectly. I rewired it all neatly and took the box off the control unit to see if it would fit inside the bike and all good. I just had to drill a couple of holes in the removable square plate under the bike so that I could attach it to the new Control unit via the heat sink aluminium block to keep it in place. I was slightly worried about overheating as the unit would no longer have its aluminium box with the fins to aid heat dissipation but now it is connected to the plate and hence the whole bike will act as a heat dissipation aid. That was the theory and I have used it daily now for a couple of weeks and inspected it today. All looks good inside so now have removed the factory display screen, as it was not connectable, and will continue to use as is. Looks like this could be a solution for a lot of people having unfixable or expensive error code issues with these bikes. Of course the thumb throttle is not strictly legal but you could easily add a cheap PAS or potentially try to connect the factory PAS. Cheers, Kevin.

 

[saneagle]

Hi. Just joined here. I have been using and building ebikes for 10 years just for personal use. Recently bought a second hand Carrera Crossfire, on the cheap, because the owner could not get rid of the error code 21. I searched forums and tried all the tricks but could not get rid of it. Finally, I took a spare control unit I had in the shed and just connected the battery, the motor and a thumb throttle and and it all works perfectly. I rewired it all neatly and took the box off the control unit to see if it would fit inside the bike and all good. I just had to drill a couple of holes in the removable square plate under the bike so that I could attach it to the new Control unit via the heat sink aluminium block to keep it in place. I was slightly worried about overheating as the unit would no longer have its aluminium box with the fins to aid heat dissipation but now it is connected to the plate and hence the whole bike will act as a heat dissipation aid. That was the theory and I have used it daily now for a couple of weeks and inspected it today. All looks good inside so now have removed the factory display screen, as it was not connectable, and will continue to use as is. Looks like this could be a solution for a lot of people having unfixable or expensive error code issues with these bikes. Of course the thumb throttle is not strictly legal but you could easily add a cheap PAS or potentially try to connect the factory PAS. Cheers, Kevin.

Great result. I don't see any hall sensor wires in your photo. Are you running it sensorless?

 

[Macca99]

Yes, I tried it without the hall wires and it runs very smoothly every time so have not bothered with them.

 

[Magikmart]

Hi Kevin.

That's excellent mate. I have a Crossfire E and a Subway E at the moment with suspected bottom bracket torque sensor failure. Do you mind if I ask what bits specifically you used? I bought a Bafang bottom bracket torque sensor from Amazon but it switches the bike of the minute it's plugged into the controller. You seem to know your stuff...I'm a bit new to all of this having only got my first Ebike last year. Any advice would be gratefully received. Cheers mate

 

[Magikmart]

Would that controller in the attached screenshot do the trick? Cheers

 

[Magikmart]

Forget it fella. I forgot how utter **** forums are

 

[thelarkbox]

Forget it fella. I forgot how utter **** forums are

Might be better to start a thread of your own detailing your problem. Chaps like @saneagle with a deep breadth of ebike know how will probably overlook this as a fixed issue..

The controller you pictured probably wouldnt be suitable for the SAME fix as above as its got hall sensor connectors and the pic lacks details specifying if it can operate without sensors connected. some can most will not.

re bottom bracket torque sensors - way beyond my limited scope but start a new thread bringing the issue to the forefront will probably grab the attention of folk with experience and knowledge i lack..

However its always worth double checking the wiring in the connectors to ensure the +5v ground and signal wires are connected consistently, the keyword 'pinout' is useful to add to google etc search strings..