E021
What code E021 means on a Bosch electric bike, what causes it, and which part to check first.
● SEVERITY: MEDIUM
Bosch E021 means: Speed sensor error. The documented cause is: Check that the magnet sits correctly on the spoke and crank arm. Reset.
What E021 means
Speed sensor error
The display shows E021 and the machine stops until the fault is cleared.
What the technical documentation says
Causes documented in the technical source published by bikedoctor.dk
| DOCUMENTED CAUSE OR CHECK |
|---|
| Check that the magnet sits correctly on the spoke and crank arm |
Replacement parts
Tools you'll need
Worth repairing, or worth replacing?
The battery: how long it lasts, when to replace it, what it costs
Before you open anything
Switch the system off and remove the battery before opening any connector. A traction battery stores enough energy to melt a tool and start a fire, and a damaged cell can ignite hours later. Never charge a swollen, dented or wet battery, and never leave one charging unattended.
What to check, in order
From the quickest check to the one that needs a technician.
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Frequently asked questions
What does E021 mean on a Bosch?
Speed sensor error The documented cause is: Check that the magnet sits correctly on the spoke and crank arm. Reset.
Can I fix E021 myself?
It depends on the part involved: Check that the magnet sits correctly on the spoke and crank arm. Reset. Clearing a filter or straightening a hose is within reach of anyone; anything behind a panel means mains electricity and water together — that is a job for a technician.
Can I keep riding with this code showing?
Yes: we document 18 other codes for Bosch on this electric bikes. They are listed at the bottom of this page, each with its own meaning.
Does the same code mean the same thing on other brands?
Often not. The same two characters can point to completely different faults depending on the manufacturer — always check the page for your own brand.