Bosch error 540: Temperature error
Bosch BES2 & BES3WarningRide with caution
The drive unit is outside its permitted temperature range, either too hot after hard use or too cold in freezing conditions. Assistance is reduced or stopped until the temperature is back within limits.
Likely causes
- Long, steep climb in Turbo with a heavy load
- Hot day plus low cadence in a high gear
- Riding in temperatures well below freezing
- Motor started immediately after coming out of a hot car or a cold shed
- Faulty temperature sensor reporting a wrong value
How to fix Bosch error 540
- Stop and switch the system off
- Hot: wait 10-15 minutes in the shade, then restart and ride in a lower mode with a higher cadence
- Cold: bring the bike (or at least the battery) into a warmer place for a while before restarting
- Avoid tuning devices and grinding low cadences
- If the code appears at normal temperatures, a dealer should check the temperature sensor with DiagnosticTool
Go to a dealer if: A dealer with DiagnosticTool is needed when 540 appears without a plausible temperature cause, or returns on every normal ride.
Warranty: A faulty sensor is covered within the 2-year warranty; heat damage from tuning or abuse is not.
Typical cost: Free if it is just temperature; a sensor repair is 150-350 EUR/USD independently, a drive unit exchange 500-1000 EUR/USD.
Warranty: A faulty sensor is covered within the 2-year warranty; heat damage from tuning or abuse is not.
Typical cost: Free if it is just temperature; a sensor repair is 150-350 EUR/USD independently, a drive unit exchange 500-1000 EUR/USD.
Still stuck? Take a photo of the display and show it to a local e-bike workshop. Bring the bike's system name (e.g. Bosch Performance Line CX) and the exact code; that saves diagnostic time and money.
Frequently asked
Can I reset Bosch error 540 myself?
Yes. Let the motor return to a normal temperature and restart; the code clears on its own.
Can I keep riding with error 540?
Usually, but with reduced or interrupted assistance and the risk of the system shutting down mid-ride. Ride home carefully or on muscle power alone; do not plan long rides until the cause is found.
Is error 540 covered by warranty?
A faulty sensor is covered within the 2-year warranty; heat damage from tuning or abuse is not.
Related Bosch codes
503 · Drive unit fault (usually overheating)605 · Battery temperature error500 · Internal fault in the drive unit
Not an official Bosch document. Compiled from workshop experience and public service information; details can differ per system version and bike brand.