Symptoms
- Display shows normal battery and speed but no motor assist
- Motor works with the throttle (if equipped) but not with pedaling
- Assist level shows selected but has no effect
- Motor cuts in and out intermittently
Likely causes
- CommonPedal-assist sensor misaligned or dirtyThe magnetic ring and sensor near the crank need to be close enough and clean to detect pedaling.
- CommonAssist mode set to zero or offAn accidental setting change can leave assist effectively disabled.
- PossibleLoose connector between the sensor and controllerVibration over time can loosen these small connectors.
- Less commonFailed motor or controllerInternal motor or controller failure is less common but possible after years of use.
What to do
- Check the assist level setting on the display and increase it if set to zero or eco with very low assist.
- Inspect the pedal-assist sensor near the crank for visible dirt, damage, or misalignment of the magnet ring and sensor.
- Turn the pedals by hand while watching the display for any indication the sensor is registering movement.
- Check the connector cable running from the sensor to the main wiring harness for looseness.
- Test the throttle if equipped, since motor response there but not with pedaling narrows the issue to the pedal sensor specifically.
- Power cycle the system by turning it off and back on.
- If the sensor is clean, aligned, and connected but the motor still doesn't engage with pedaling, an e-bike shop should test the controller and sensor.
Tools and parts
- Small screwdriver
Pedal assist sensorSearch: “e-bike pedal assist sensor replacement”
When to call a pro
An e-bike shop can test the pedal-assist sensor and controller directly and replace whichever component has failed.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.