Loose, dirty, or partially seated connectors, especially around the display harness, speed sensor, and motor cable.
Bafang Error Codes List: Meanings, Quick Fixes, and When to Contact a Shop
Written by: Chris Van Leuven | January 16, 2026 | Time to read 7 min
Bafang e-Bike error codes explained: what they mean, quick safe fixes, and when to visit a local shop.
More about the Author: Chris Van Leuven
Chris is a writer, climber, and founder of Yosemite E-Biking in Mariposa, CA. When he’s not tackling Sierra Foothills trails or scaling rock walls, he’s crafting adventure stories with his boxer, Fenster. His work has appeared in Outside, Men’s Journal, Gripped, and Best American Sports Writing.
Walk into any bike shop or scroll through e-Bike forums, and chances are you’ll come across Bafang. The company’s drive systems—motors, displays, controllers, and all the wiring in between—power everything from daily commuter bikes to heavy-duty cargo haulers and even home-built conversions. Riders gravitate toward Bafang for its reputation: reliable, powerful, and easy to service, with options that fit just about every budget and riding style.
Error codes usually aren’t the end of the world, but they are the bike’s way of saying: “Pause. Something isn’t reading right.” Bafang shows up on a ton of e-Bikes for a reason: it’s widely available, it works, and it tends to hold up well when the basics are taken care of (clean, dry, maintained). Still, if you ride a lot, travel with your e-Bike, or ride in the weather, an error code will eventually pop up.
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Table of Contents
Before You Start: Quick Safety and Connection Check
Bafang Error Codes: Quick Reality Check
Error Code 05: Throttle Not in Place
Error Code 07: System Overvoltage Protection
Error Code 08: Hall Signal in Motor Abnormal
Error Code 09: Phase Wire in Motor Abnormal
Error Code 10: Motor Overtemperature Protection
Error Code 11: Motor Temperature Sensor Abnormal
Error Code 12: Controller Current Sensor Abnormal
Error Code 21: Speed Sensor Abnormal
Error Code 30: Communication Abnormal
Error Code 42: Discharge Voltage of Battery Pack Is Too Low
Before You Start: Quick Safety and Connection Check
When a code pops up:
- Pull over and power the e-Bike off completely.
- If the battery is removable, pull it, wait about 60 seconds, then reinstall it.
- If you notice melting plastic, a burnt smell, heat discoloration, or a swollen battery, stop riding and go straight to a shop.
Then do the most common fix: reseat the connectors you can reach (display/HMI, main harness, speed sensor, brake cutoffs, throttle). Bent pins, moisture, grit, and half-seated plugs cause many “mystery” codes.
Here are the all Bafang motor models:
- M400 (Max Drive)
- M420
- M510
- M600
- M620 (Ultra Drive)
- HR-series rear hub motors
- BBS02 (conversion mid-drive)
- BBSHD (conversion mid-drive)
Bafang Error Codes: Quick Reality Check
Bafang code numbers aren’t universally consistent across every display and motor system. The same “themes” appear everywhere (voltage, heat, sensors, communication), but the exact code varies by system and display. Use this as a quick triage, then confirm in your display manual if a code keeps returning.
Error Code 05: Throttle Not in Place
Meaning: The system thinks the throttle isn’t back at “zero.”
Try: make sure it isn’t physically stuck or rubbing the grip, reseat the throttle connector, then restart.
Error Code 07: System Overvoltage Protection
Meaning: The system thinks the throttle isn’t back at “zero.”
Try: make sure it isn’t physically stuck or rubbing the grip, reseat the throttle connector, then restart.
Error Code 08: Hall Signal in Motor Abnormal
Meaning: The controller isn’t getting a clean motor position signal.
Try: Re-seating the motor connector, checking for moisture/corrosion, and inspecting the harness for rub points.
Error Code 09: Phase Wire in Motor Abnormal
Meaning: A problem between the controller and motor phase wiring.
Try: inspect the main harness/extension cable for crushing or heat damage. If anything is melted or smells burnt, stop riding.
Error Code 10: Motor Overtemperature Protection
Meaning: The motor is hot and is protecting itself.
Try: power down and cool off. Next attempt: lower assist, shift earlier, and keep cadence up.
Error Code 11: Motor Temperature Sensor Abnormal
Meaning: The motor temperature sensor signal is abnormal (only on systems equipped with a temp sensor).
Try: power cycle once and let the bike return to normal temperature. If it returns, plan on diagnostics.
Error Code 12: Controller Current Sensor Abnormal
Meaning: The controller's current sensing is abnormal.
Try: check power connections for looseness/corrosion/heat signs, then power cycle and retest in a lower assist mode.
Error Code 21: Speed Sensor Abnormal
Meaning: The bike can’t read wheel speed correctly, so assist may cut in and out.
Try: check the spoke magnet hasn’t slipped, realign the magnet and sensor, and keep clearance reasonable (often around 10–15 mm, depending on your setup). Inspect the sensor cable and reseat the connector.
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Error Code 30: Communication Abnormal
Meaning: A communication fault (commonly related to the HMI/display cable or its connection).
Try: power cycle, reseat accessible connectors (display/HMI and main harness), and check cable routing near the stem/head tube for pinch points.
If it keeps returning: this is where a shop’s diagnostic tools (and swap-testing cables/displays) can save you a lot of trial-and-error.
Error Code 42: Discharge Voltage of Battery Pack Is Too Low
Meaning: The battery voltage is too low under load, or the battery needs charging.
Try: fully charge and retest. In cold weather, warm the battery indoors first. On climbs, use lower assist and an easier gear to reduce voltage sag.
When to Stop DIY and What to Tell the Shop
Stop troubleshooting if:
- The same code returns immediately after 1–2 clean restarts.
- Assist cuts in and out unpredictably (especially with voltage, current, or communication codes).
- You see corrosion, water in a port, burnt smells, melted plastic, or damaged wiring.
Tell the shop:
- The exact code and when it happens (startup, climb, random cutout).
- Battery percentage, plus whether it was a cold day or a hot day.
- Anything recent: rain/wash, transport, charger change, firmware update, accessory install.
Prevent Repeat Errors
- Keep connectors clean and dry, and avoid pressure washing around the motor, battery, and ports.
- After transporting the e-Bike, do a quick scan near the stem/head tube for pinched cables.
- On long climbs, shift early and keep cadence up.
- Let the e-Bike dry before charging if it got wet.
If you're troubleshooting a recurring error and considering a new daily ride, it helps to browse by category, such as electric bikes, used electric bikes, electric city bikes, cargo e-Bikes, folding electric bikes, or electric mountain bikes.
Frequently Asked Questions
What’s the most common cause of a Bafang error code?
Can I keep riding with an error code?
If it clears and the assistance feels normal, you can usually ride home gently. If it returns immediately or involves voltage, heat, controller, or communication faults, back off and get it checked.
When should I contact a shop?
If the code returns right after a clean restart and a connector check, or you see any heat damage or moisture inside connectors, it’s time for diagnostics.
Key Takeaways
- Most Bafang error codes trace back to connectors, sensors, voltage, heat, or communication.
- Start simple: full power-off restart, battery reseat, then a careful connector and sensor check.
- If the same code keeps returning, a local e-Bike shop with diagnostic tools will usually solve it faster than parts swapping.
