BOSCH GEN4 TUNING (2020/2021): WHAT YOU NEED TO KNOW
Understanding Bosch Gen4 Anti-Tuning Protection
Bosch Gen4 e-bike motors, introduced in model years 2020 and 2021, are equipped with integrated anti-tuning software. This system actively detects modifications and triggers Error Code 504, which drastically reduces or disables motor support. In such cases, the motor enters emergency mode. After 90 minutes of riding in this reduced mode, full functionality may temporarily return—but the detection system resets. After the third incident, only a certified Bosch dealer with diagnostic tools can unlock the motor.
Bosch’s goal is clear: prevent unauthorised tuning.
THE BOSCH GEN4 TUNING OVERVIEW
Despite Bosch's efforts, a wide range of tuning devices have been developed to work with Gen4 motors without triggering error codes. These devices remove the 25 km/h speed limit while bypassing Bosch’s detection system. All tuning devices listed in our shop have been extensively tested on original Gen4 Bosch drives.
Note: Bosch Gen2 and Gen3 drives running firmware version 1.8.4.0 or higher also contain anti-tuning protection. In these cases, Gen4-compatible tuning devices are often required.
⚠️ COMPATIBILITY NOTE
Tuning devices listed here are not compatible with the Bosch Smart System (BES3) introduced in 2022. You’ll find dedicated solutions for BES3 systems in our separate Bosch Smart System tuning guide.
BOSCH GEN4 MOTOR MODELS (2020/2021)
The “Gen4” label refers to updated versions of existing drive systems, primarily the Performance Line and Performance Line CX. Below is a summary of the key variants:
PERFORMANCE LINE CX GEN4 (MY20):25 km/h support, 85 Nm torque, up to 340% pedal assistance, support for cadences over 120 rpm. More compact, lighter, and with minimal pedal resistance above 25 km/h.
PERFORMANCE LINE SPEED GEN4 (MY20):45 km/h support, 85 Nm torque, 340% pedal assistance, high cadence compatibility.
CARGO LINE GEN4 (MY20):25 km/h support, 85 Nm torque, up to 400% assistance, optimized for heavy loads.
CARGO LINE SPEED GEN4 (MY20):45 km/h support, same high torque and support profile as above.
PERFORMANCE LINE “CRUISE” GEN4:25 km/h, 65 Nm torque, 300% pedal support, now includes eMTB mode. Exceptionally low resistance when not under power.
TIPS FOR SAFE TUNING WITH BOSCH GEN4
Stay under 35 km/h: Most tuning manufacturers recommend setting the motor limit no higher than 33–35 km/h. Higher values increase the risk of triggering Bosch’s detection software.
Avoid unnecessary firmware updates: Updates can add tuning protection even to previously unaffected bikes. Unless required for bug fixes, we suggest skipping them.
Firmware 1.0.3.0 recommended: For certain Performance Line motors, this version reduces the chance of false-positive 504 errors. The phrase “never change a winning team” applies here—if your bike runs smoothly, avoid unnecessary updates.
BEST BOSCH GEN4 TUNING DEVICES (2020/2021)
We’ve tested and selected the most effective tuning devices for Bosch Gen4 drives:
VOLspeed V4: Allows tuning adjustment directly through the Bosch display, with user-friendly setup and limits.
SpeedBox: A classic tuning module offering clean integration and a proven track record.
BadassBox 4: A contactless, removable external solution that doesn’t interfere with internal systems.
All of these solutions are also backward compatible with Gen2 and Gen3 drives running firmware version 1.8.4.0 or newer.
WHICH BOSCH TUNING IS RIGHT FOR YOU?
If you prioritise quick removal and minimal technical setup, the BadassBox is a great choice. For more advanced, app-based control and off-road customisation, Speedbox is the top recommendation. Riders using their e-bike exclusively off-road may prefer SpeedBox for maximum unlock performance.
⚠️ NOT SUPPORTED:
Bosch Smart System (BES3) – requires separate tuning devices
Bosch Classic Line (Gen1) – not compatible with Gen4 devices
