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E-bike won't turn on? Work through this in order
Nine times out of ten an e-bike that is completely dead has a battery problem: empty, not seated, or switched off at the pack. Work from the battery outwards before you suspect the display or the motor.
Quick checks, in order
- Check the battery's own indicator first: press the button on the pack. No LEDs at all means the pack is either flat or in deep-sleep protection, and no amount of pressing the display button will help.
- Put the battery on the charger for 20-30 minutes, then try again. A pack that dropped below its cut-off voltage will not wake the system until the charger has lifted it.
- Remove the battery and refit it firmly. Listen for the click of the lock and check the key is turned fully to the locked position; on many frames the contacts only make when the lock is engaged.
- Hold the power button for 3+ seconds, not a tap. On Bosch Purion/Intuvia it is on the display, on Kiox/Smart System it is on the remote or the battery, on Shimano it is the small button on the battery or display, on Bafang it is on the handlebar remote.
- Look at the display cable and remote cable where they enter the handlebar. A quarter-turn loose connector or a pin pushed back is the most common cause of a bike with a working battery and a dead display.
- If the bike has a separate display that clips into a mount (Intuvia, Nyon, some Shimano), remove and refit the display and clean the contacts on the mount with a dry cloth.
- If you have a second battery or a friend with the same system, swap it in. It answers the battery-or-bike question in thirty seconds.
Likely causes
Battery fully discharged into protection mode
How to tell: Pressing the pack's button shows nothing, or one LED that blinks. The bike was left for weeks, or ridden until it stopped.
Fix: Charge for at least 30 minutes before testing. If the charger light never changes from standby, the pack may be below the level the BMS allows charging from; that needs a shop or the manufacturer.
How to tell: Pressing the pack's button shows nothing, or one LED that blinks. The bike was left for weeks, or ridden until it stopped.
Fix: Charge for at least 30 minutes before testing. If the charger light never changes from standby, the pack may be below the level the BMS allows charging from; that needs a shop or the manufacturer.
Battery not making contact
How to tell: The pack shows charge on its own LEDs, but the display stays dark. Often after refitting the battery or after a bumpy ride.
Fix: Remove, inspect the contact block for dirt or corrosion, refit and lock. Bent contact springs in the frame-side connector need a shop.
How to tell: The pack shows charge on its own LEDs, but the display stays dark. Often after refitting the battery or after a bumpy ride.
Fix: Remove, inspect the contact block for dirt or corrosion, refit and lock. Bent contact springs in the frame-side connector need a shop.
Loose or damaged display / remote cable
How to tell: Battery good, motor sometimes runs briefly, display flickers or comes on when you wiggle the cable at the stem.
Fix: Unplug and replug the connector at the display and at the remote, check for pushed-back or green pins. A cut cable from crash damage needs replacing.
How to tell: Battery good, motor sometimes runs briefly, display flickers or comes on when you wiggle the cable at the stem.
Fix: Unplug and replug the connector at the display and at the remote, check for pushed-back or green pins. A cut cable from crash damage needs replacing.
Display battery empty (Bosch Kiox 300/500, Nyon, Shimano wireless units)
How to tell: Displays with an internal battery that were left off the bike for months will not wake even with a full pack.
Fix: Refit the display on the bike, switch the system on from the remote or pack, and leave it powered for an hour so the display battery recharges.
How to tell: Displays with an internal battery that were left off the bike for months will not wake even with a full pack.
Fix: Refit the display on the bike, switch the system on from the remote or pack, and leave it powered for an hour so the display battery recharges.
Blown main fuse (hub-drive and older systems)
How to tell: Battery good, nothing works, and the bike has a visible fuse on the battery mount, controller box, or inside the battery cover.
Fix: Replace with the same rating only. If it blows again there is a short in the controller or wiring, stop there.
How to tell: Battery good, nothing works, and the bike has a visible fuse on the battery mount, controller box, or inside the battery cover.
Fix: Replace with the same rating only. If it blows again there is a short in the controller or wiring, stop there.
Water in the display or controller
How to tell: Stopped working after rain, a pressure wash, or being stored outside. Condensation visible inside the display glass.
Fix: Remove the battery, dry the bike indoors for 24-48 hours, then retry. See the water-damage guide before doing anything else.
How to tell: Stopped working after rain, a pressure wash, or being stored outside. Condensation visible inside the display glass.
Fix: Remove the battery, dry the bike indoors for 24-48 hours, then retry. See the water-damage guide before doing anything else.
Failed BMS inside the battery
How to tell: The pack shows nothing on its own LEDs even after a long charge, and the charger goes straight to green.
Fix: This is not user-serviceable. Have the pack tested by a dealer with the diagnostic tool; never open the case.
How to tell: The pack shows nothing on its own LEDs even after a long charge, and the charger goes straight to green.
Fix: This is not user-serviceable. Have the pack tested by a dealer with the diagnostic tool; never open the case.
By drive system
- Bosch: Check the battery LEDs on the pack first. Kiox/Nyon have their own internal battery that goes flat if left off the bike; refit and power from the remote. Smart System bikes can be switched on from the battery button as well as the remote.
- Shimano STEPS: The power button is on the battery for most STEPS bikes, not the display. If the battery LEDs light but the display doesn't, check the EW-SD cable at the display; a half-clicked E-Tube plug is common after a crash.
- Bafang: Hold the power button on the remote for 3 seconds. Bafang mid-drives have an inline fuse on the battery lead on many builds; check it. A dead remote with a live battery is usually the 5-pin display connector at the bars.
- Yamaha PW: The power button is on the display unit. Yamaha packs need the key in the lock and turned fully; if the LED bar on the pack lights, the problem is downstream of the battery, usually the display connector.
- Generic: Hub-drive bikes with a generic LCD (KT, King-Meter, etc.): confirm the pack switch is on, check the inline fuse, then hold the M or power button for 3 seconds. A dark LCD with a charged pack is nearly always the display connector or the controller.
When to stop: Stop and go to a shop if the battery shows nothing after 30 minutes on the charger, if a fuse blows twice, or if there is any sign of water inside the battery or a burnt smell from the controller.
Related error codes
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
The battery shows full but the bike is dead. Is the battery bad?
Probably not. A pack that reports charge on its own LEDs is alive; the fault is in the connection to the bike or in the display cable. Refit the battery, then check the display and remote connectors.
How long should I leave it on the charger before deciding it's dead?
Thirty minutes is enough for a deeply discharged pack to wake up and start charging normally. If the charger stays on standby or goes straight to green after that, the pack needs a diagnostic test.
Can I bypass the display to test the motor?
No. On Bosch, Shimano and Yamaha the display or remote is the system's on-switch and part of its authentication; the motor will not run without it. On generic hub systems some controllers allow it, but it tells you nothing you can't learn by testing the display connector.