Electric bikes.
We have documented 126 electric bikes fault codes from published technical sources. 115 of them (91%) also carry the cause, not just the meaning. The most frequent subjects are the speed sensor, the battery, wiring and communication. On 13 codes the same code means different things depending on the brand — always check yours.
Most frequent fault codes
Each code below comes from a published source, with the cause and the check to run. We never invent a cause we cannot document.
| Code | What it means | Cause & what to check |
|---|---|---|
| 02 Bafang | Throttle fault | Throttle stuck, shorted, or disconnected |
| 03 Bafang | Brake lever fault | Brake sensor signal stuck (handlebar lever or hydraulic switch) |
| 04 Bafang | Speed sensor fault | PAS or wheel-speed sensor missing, dirty, or misaligned |
| 05 Bafang | Motor hall‑sensor fault | Internal hall sensor inside the motor damaged |
| 06 Bafang | Controller overheating | Controller temperature exceeded safe limit |
| 07 Bafang | Over‑voltage or under‑voltage | Battery voltage outside controller range |
| 08 Bafang | Controller internal fault | Short or component failure in the controller |
| 09 Bafang | Battery communication fault | BMS not talking to the display via the serial line |
| 10 Bafang | Motor phase‑wire fault | Short or break in phase wires (blue, yellow, green) |
| 12 Bafang | Restart once | |
| 21 Bafang | Check the wheel magnet position against the sensor | |
| 25 Bafang | Restart with feet off the pedals so the sensor can zero | |
| 30 Bafang | Check all cable connectors between display, controller and battery | |
| C01 Bafang | Throttle error (voltage out of range) | Check that the throttle isn't stuck in a fixed position. Reset. |
| C02 Bafang | Motor fault or motor temperature too high | Let the motor cool for 10 minutes. Check that ventilation holes are not blocked. |
| C05 Bafang | Communication error (controller to display) | Check all cable connectors along the seat tube. Clean contacts. Reset. |
| C06 Bafang | PAS sensor error (pedal sensor) | Check that the PAS magnet sits correctly on the crank drive and is not damaged. |
| C09 Bafang | Speed sensor error | Check wheel sensor and magnet. Reset. |
| 410 Bosch | Power off, wait 10 seconds, power on (fixes 40% of cases) | |
| 414 Bosch | Power cycle the system | |
| 418 Bosch | Power cycle the system | |
| 422 Bosch | Power cycle the system | |
| 430 Bosch | Internal battery of the on-board computer empty (not with BUI350) | |
| 431 Bosch | Software version error | |
| 440 Bosch | Restart the system once | |
| 450 Bosch | Restart the system once | |
| 460 Bosch | Try a different charger if available | |
| 500 Bosch | Internal error in the drive unit | |
| 502 Bosch | Check light cable connections | |
| 503 Bosch | Speed Sensor Error | Speed sensor error |
| 504 Bosch | Manipulation of the speed signal | |
| 510 Bosch | Stop and let the motor cool for 15 to 20 minutes | |
| 530 Bosch | Battery Error | Error in communication with the ebike battery |
| 550 Bosch | Disconnect the third-party device | |
| 602 Bosch | Perform a full charge cycle (drain to 0%, charge to 100%) | |
| 606 Bosch | Communication Error | Check wiring harness for pinches |
| 640 Bosch | Internal battery fault | |
| 7xx Bosch | Gearbox error | |
| C01 Bosch | Throttle error (voltage out of range) | Check that the throttle isn't stuck in a fixed position. Reset. |
| C02 Bosch | Motor fault or motor temperature too high | Let the motor cool for 10 minutes. Check that ventilation holes are not blocked. |
What actually breaks
Counted on the 126 codes on this page, not estimated.
| subject | codes | share |
|---|---|---|
| the speed sensor | 34 | 27% |
| the battery | 31 | 25% |
| wiring and communication | 21 | 17% |
| the motor | 20 | 16% |
| the controller | 13 | 10% |
| overheating | 10 | 8% |
| the throttle | 5 | 4% |
| the brake cut-off | 4 | 3% |
The parts that fail
The components behind the codes above: pump, heating element, seal, filter.
Brands covered
Frequently asked questions
Answers counted on our own data, with the sources cited at the bottom of the page.
What is the most common electric bikes fault code?
In our data the code that appears on the largest number of brands is 02. On Bafang it means: Throttle fault
Does the same code mean the same thing on every brand?
No, and this is the single most useful thing to know. We found 13 codes that appear on two or more brands with different meanings. For example 02: on Bafang it means «Throttle fault», on Yamaha it means «Throttle error».
What goes wrong most often on a electric bikes?
Counting the causes we documented: the speed sensor (27%), the battery (25%), wiring and communication (17%), the motor (16%). This is what the codes actually describe.
Which brands are covered?
For electric bikes we currently document codes for: Bosch, Shimano, Yamaha, Bafang, Gotrax, Segway, Tq, Brose, Panasonic. The list grows as we verify new sources.
How reliable is that motor, that battery, that brand?
Beyond fault codes and technicians, we rate the reliability of motor systems, batteries and brands — a transparent score that owes nothing to the manufacturers.