E-bike controller
The controller is the electronics box that runs the motor. Replace it only with the part matched to your bike and display, plugged in at its connectors, or have a pro do it.
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The controller is the box of electronics between the battery and the motor. Grin Technologies explains that it turns the battery's DC power into the three-phase power a hub motor needs and decides how much power reaches the motor from the throttle, the pedal sensor and its own current limit (Grin, e-bike parts explained).
A controller is matched to your bike and swapped at its external plugs, or by a pro. Never open a controller, splice its wires, or bypass a sensor or cutoff. Remove the battery before you unplug anything, and if you aren't sure the controller is the fault, find a shop.
What it's used for
A failed controller can leave the bike dead, cut the motor in and out, or put an error on the display. Work through E-bike won't turn on, Motor cuts out and E-bike error codes first, since a loose plug or a stuck brake sensor can look just like a bad controller. A tech can confirm it with the no power diagnosis.
What to look for
- The exact part for your model and version. Rad Power Bikes publishes a separate controller guide per model. Its RadRunner guide covers the Runner 1, Runner 2 and Runner 1 Plus, the Runner 3 Plus has its own, and Rad says its support team decides whether a controller needs replacing (Rad RadRunner controller guide).
- Throttle or no throttle. Ride1Up sells separate throttle and non-throttle controllers and displays for the Roadster v2 (Ride1Up Roadster parts).
- Voltage and current that suit the motor. Grin notes that a controller works within a voltage range and has a current limit, and that a high-current controller on a small motor risks overheating it (Grin).
- A display that speaks the same protocol. Displays have no standard protocol, so they are usually tied to one controller (Grin). Treat the controller and display as a matched pair.
- Hall sensor support. Grin says knowing whether the motor has hall sensors is essential when matching a motor and controller (Grin).
- Setup after fitting. On some Aventon bikes a replaced controller is set up through the Aventon app (Electric Kicks help center).
- Like for like. Skip higher-power upgrade units.
Typical price
- Aventon lists the Aventon Controller at $83.99 on its parts store (read Nov 9, 2026) (Aventon).
- Area 13 E-Bikes lists the controller for its own Blackbird e-bike at $89.99 (read Nov 9, 2026) (Area 13).
- California Ebike lists a CANBUS controller for the Bafang BBSHD at $125 (read Nov 9, 2026) (California Ebike).
- Ebike Supershop lists a Super73 S2, Z Miami Core and ZX Core legacy controller at $249 (read Nov 9, 2026) (Ebike Supershop).
Where to buy
- Your bike maker's parts store or support team, for example Ride1Up, Aventon or Rad Power Bikes support.
- For Bafang kit systems, a Bafang service center such as California Ebike.
- Independent parts specialists, listed in Where to buy e-bike repair parts.
- A local shop, through find a shop.
Guides that use it
- No power diagnosis
- Inspect and clean connectors
- Check brake cutoff and throttle
- Rad Power Bikes troubleshooting
Sources
- Grin, e-bike parts explained, ebikes.ca
- Rad RadRunner controller guide, support.radpowerbikes.com
- Ride1Up Roadster parts, ride1up.com
- Electric Kicks help center, electrickicks.gorgias.help
- Aventon, aventon.com
- Area 13, area13ebikes.com
- California Ebike, california-ebike.com
- Ebike Supershop, ebikesupershop.com
Stuck after these checks? Find a shop near you.
Guides that use this
- Apollo Go: E7 error, a motor won't respond or feels locked
- Aventon Level.2, Pace, Sinch and Aventure: error 21 or W03, motor cuts out on long climbs
- Aventon Level.2, Pace, Sinch and Aventure: error 23 or 24, motor phase or hall fault
- Aventon Level.2, Pace, Sinch and Aventure: error 25, motor won't engage or cuts out without braking
- Aventon Level.2, Pace, Sinch and Aventure: error 30, display and controller not communicating
- Aventon Level.2: parts and specs
- Aventon Pace 500.3: parts and specs
- Bafang BBS01, BBS02 and BBSHD: replacement controller and display options
- Gotrax G3, G4, GMAX and GMAX Ultra: error 4 motor signal failure or error 6 motor blocking
- Heybike Cityrun, Tyson, Ranger S and Mars 2.0: error 25, bike won't accelerate
- Heybike Mars, Ranger, Cityscape, Cityrun, Tyson and more: error 30 on the display
- Hiboy S2, S2 Pro and KS4: display to controller communication error (E3, or E1 on the S2 Lite)
- Himiway Zebra and Cruiser: error 30 abnormal communication on the display
- Hub motor e-bike dead controller: matching a universal KT style replacement
- Lectric XP 3.0: parts and specs
- Lectric XP, XP Lite and XPedition: E007 motor fault on the display
- Lectric XP4, XPeak 2 and XP Trike 2: E003 pedal assist sensor fault
- Lectric XP4, XPeak 2 and XP Trike 2: E010 or E011 display communication failure
- Onewheel dead controller: factory repair or a VESC-based conversion
- Rad LCD display bikes dead controller or display: replacement options
- Rad Power Bikes RadCity 3, RadCity 4 and RadCity Step-Thru 3: error 30 on the LCD display
- Rad Power Bikes RadMini 4: error 30 on the LCD display
- Rad Power Bikes RadMission: pedal assist level 2 light flashing, motor won't run (error 24)
- Rad Power Bikes RadMission: won't power on, or all pedal assist lights flash (error 30)
- Rad Power Bikes RadRover 6 Plus: error 30 on the display or the bike won't power on
- Rad Power Bikes RadRunner 1 and RadRunner 2: parts and specs
- Rad Power Bikes RadRunner 1, 2 and Plus: error 24 or assist level 2 flashing
- Rad Power Bikes RadRunner 3 Plus: parts and specs
- Rad Power Bikes RadRunner Plus: parts and specs
- Rad Power Bikes Radster, RadWagon 5 and RadExpand 5 Plus: error 21 or 23 after climbing hills
- Rad Power Bikes Radster, RadWagon 5 and RadExpand 5 Plus: error 24 on the color display
- Rad Power Bikes RadWagon 4: error 30 on the display
- RadRunner dead controller or display: aftermarket replacement options
- Ride1Up Core-5, 500 Series, 700 Series and LMT'D: error 21 or power cuts out on long climbs
- Ride1Up Core-5, 500 Series, 700 Series and LMT'D: error 30 communication error
- Ride1Up Core-5: parts and specs
- Ride1Up Core-5: powers on, wheel spins for a second, then stops
- Segway Ninebot E2 Pro: error 42, motor not calibrated
- Segway Ninebot E2 Pro: error 51, controller overvoltage after charging
- Set up a KT or Bafang display within your e-bike class
- Super73 R, S and Z series: display on, but the motor won't run or cuts out
- Velotric Discover 1 and Nomad 1: error code 21 to 30 on the display
- Velotric Discover and Nomad: display on, but the motor doesn't respond
If these steps didn't fix it, find a shop near you in our partner network. For battery or wiring trouble, look for shops marked Battery and electrical.
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