Bosch error codes: what is the problem and how can it be solved?
When your Bosch e-bike displays an error code on the screen, there is usually no reason to panic. Most messages refer to fairly simple problems, such as an incorrect sensor position, loose contact points, or a dead internal display battery. Thanks to the integrated diagnostic function, the system indicates precisely where the problem lies, and you can often solve it yourself without having to go to a repair shop immediately. In this guide, you will find an overview of the most common Bosch error codes, their meanings, and the steps to take to resolve them quickly.
Written by: Hanna Stevens | December 3, 2025 | Reading time: 5 minutes
More about the author: Hanna Stevens
Hanna is an avid cyclist who loves exploring new routes and sharing her experiences to inspire others to get on their bikes more often.
Key findings
- Many Bosch error codes can be easily resolved by yourself, such as problems related to the speed sensor, misaligned magnets, or moisture on the contact points.
- Restarting the system or cleaning up connections is sufficient to eliminate most of the messages.
- However, internal engine error messages or persistent codes require a visit to a Bosch specialist repair shop.
1. Error code 503
Problem:
Code 503 is the most common code in the Bosch system. It indicates a problem with the speed sensor. This is usually due to misalignment between the sensor and the magnet. The magnet is attached to a spoke on the rear wheel and must pass in front of the sensor with each turn of the wheel to enable the speed to be calculated.
If these components are not correctly aligned, speed cannot be detected and motor assistance is disabled. The ideal distance between the sensor and the magnet should be between 8 and 14 millimeters.
Solution:
Check the position of the speed sensor and magnet. Adjust the magnet on the spoke so that it is correctly aligned with the sensor. The sensor can be loosened using a Phillips screwdriver.
Then restart the system. If the problem persists, contact a Bosch specialist workshop.
2. Error code 523001
Problem:
Code 523001 is the successor to code 503 and appears in the Bosch Smart System. As it replaces 503, it probably also indicates a problem related to the sensor or speed detection.
Solution:
Same procedure as for code 503: check the alignment of the sensor and magnet, then restart the system.
3. Error code 414
Problem:
This code indicates a connection problem with the control unit. The display is no longer able to communicate with the system.
This problem often occurs in humid weather: humidity can cause slight corrosion on the copper contact points, resulting in a loss of connection.
This code belongs to the category of problems relating to the connection between the screen/control, the motor, and the battery.
Solution:
Clean the contact points. You can use a spray for electrical contacts. Check all accessible connections and ports.
If the message persists after these checks, contact an authorized Bosch center.
4. Error code 430
Problem:
Code 430 means that the internal battery of the on-board computer (the display) is discharged. This often happens when the main battery is always recharged outside of the bike.
Solution:
The screen recharges when the e-bike is plugged in while the main battery remains installed in the bike.
You can also recharge the screen via the micro-USB port.
Turn on the bike using the button on the battery (near the charge indicator LEDs) or recharge the screen via USB.
5. Key icon (Bosch maintenance message)
Problem:
Although this is not an error code, it is one of the most common messages. The appearance of a small wrench indicates that it is time for the first service or annual maintenance.
This notification depends on factors such as the number of kilometers traveled, frequency of use, and age of the bike.
Solution:
Schedule a service. During this service, the system is connected to a computer, a software update is performed, and the entire bike is checked (cable tension, brakes, spoke tension, etc.). You can continue riding despite the message, but a service is strongly recommended.
6. Error code 500
Problem:
Code 500 indicates an internal error in the drive unit.
Solution:
Restart the system by turning off the bike, waiting ten seconds, and then turning it back on.
If the message persists, a visit to a Bosch specialist workshop is essential.
7. Error code 502
Problem:
This code indicates a fault in the lighting connected to the Bosch system.
Solution:
Check the headlight operation as well as the associated wiring and connections.
Restart the system by turning the e-bike off and then on again.
If the error persists, contact a Bosch workshop.
8. Error code 504
Problem:
Code 504 may indicate an electronic problem, incorrect magnet position (as with code 503), or—more critically—detection of engine tampering or modification (tuning).
While this code is displayed, assistance is reduced.
Solution:
Check the position of the sensor and magnet (distance 8–14 mm). Check that no tampering has been carried out.
If the error persists, visit a Bosch specialist workshop.
Summary
| Problem | Solution | |
|---|---|---|
| 503 | Speed sensor or magnet misaligned | Align sensor/magnet (0.3–5.5 in.); restart |
| 523001 | Sensor problem in the Smart System (successor to the 503) | Check and align sensor/magnet; restart |
| 414 | The screen is no longer communicating (moisture/corrosion) | Clean the contacts; check the cables |
| 430 | Internal screen battery discharged | Charge via the main battery or USB |
| Key icon | Maintenance required | Schedule a review; update + full check |
| 500 | Internal engine error | Restart; if the problem persists: workshop |
| 502 | Lighting error (cables/connections) | Check the wiring; restart; workshop if necessary |
| 504 | Electronic error, incorrect magnet position, or tuning detected | Check the magnet; rule out any tampering; workshop if the problem persists. |
FAQ
Can I continue driving with a Bosch error code?
For certain notifications (such as the key icon), yes.
However, for errors related to sensors, the engine, or the battery, assistance may be reduced or stopped. In the event of a serious code, avoid continuing to drive.
Does an error code disappear on its own after a restart?
Often, yes. Bosch recommends turning the bike off for ten seconds and then turning it back on.
If the message keeps coming back, there is an underlying problem.
Is it safe to adjust the speed sensor or magnet yourself?
Yes, as long as you limit yourself to correcting the position or cleaning the components.
Never open the motor or battery: it is dangerous and will void the warranty.
Can rain or humidity cause error codes?
Yes. Code 414 (screen problem) appears very often due to moisture or slight corrosion of the contact points.
When should I take it to a repair shop?
For codes indicating an internal engine problem (such as 500), suspected tampering (504), a bad connection that cannot be cleaned, or codes that keep reappearing despite your corrections.