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Why is my electric bike not working?

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In short

Most e-bikes that stop working have a simple cause: a flat or badly seated battery, a key or switch left off, a loose or wet connector, or a brake cut-off sensor stuck on. Work through the battery, the display, the connectors and the brake levers in that order. If the bike still has no assist, a sensor, controller or motor fault is likely and a bike shop should look at it.

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An e-bike that will not power on, or switches on but gives no assistance, is frustrating, especially on the way to work. The good news is that many faults are connections and settings rather than broken parts. This guide takes you through a logical order of checks, from the battery to the motor cable, using only your eyes and hands. Systems differ between brands, so use your manual for specific error codes and reset procedures, and do not open sealed parts like the battery or motor.

Quick checks first

Before anything else, run through these basics. They catch a surprising number of problems.

  • Is the battery charged? Press its own level button if it has one.
  • Is the battery fully clicked into its mount and locked?
  • If the battery has an on/off switch or key, is it on?
  • Did you turn on the display or control unit, and is an assist level selected (not 0 or off)?
  • Is either brake lever slightly pulled, or a lever sticking?

Step 1: the battery

Take the battery off and look at the contacts on the battery and the mount. Dirt, corrosion or bent pins can stop power reaching the bike. Clean them gently with a dry cloth. Refit the battery firmly; you should feel or hear it lock.

If the battery will not show any charge, or will not charge at all, see our battery not charging guide. Some batteries shut down to protect themselves after being run completely flat or left very cold, and may need time at room temperature on the charger.

Note:Lithium battery safety: charge only with the charger supplied for your battery, do not leave it charging unattended or overnight while you sleep, charge away from escape routes such as hallways, and stop using any battery that is swollen, cracked, leaking, very hot or smells odd. See the London Fire Brigade guidance on lithium batteries.

Step 2: the display and controls

If the display lights up, read any error code and look it up in your manual. If it stays blank, the problem may be the display itself, its plug or the power supply to it. Our guide to an e-bike display not working covers this in more detail.

If the display works but shows no assist, check the assist level is above zero and that any walk-assist or settings menu has not been left in an unusual mode.

Step 3: connectors and cables

Follow the cables from the handlebar down to the motor and controller. Look for plugs that have pulled apart, pins that are bent, and cables that are pinched, cut or rubbing on the frame or wheel. Hub motor cables at the rear dropout often get strained when the wheel is removed.

Water in a connector can cause intermittent or total loss of power. If you have recently washed the bike or ridden in heavy rain, let it dry indoors before testing again. Our cleaning guide explains how to avoid it next time.

Step 4: brake cut-off sensors

Many e-bikes have sensors in the brake levers that cut motor power when you brake. If a lever does not return fully, or a sensor magnet has moved, the system thinks you are braking and gives no assist. Squeeze and release each lever firmly. On some bikes you can unplug a lever sensor to test it, but plug it back in afterwards because it is a safety feature.

Speed sensors matter too. On many rear hub and mid-drive bikes, a magnet on the spoke or disc passes a sensor on the frame. If the magnet has moved, the system may show zero speed or an error and refuse to assist.

When to see a bike shop

If the battery is charged, the display works, the connectors are sound and the brake sensors are fine, the fault may be in the pedal-assist sensor, controller or motor. These need diagnostic tools or specialist parts. A bike shop that services e-bikes, or the maker's service network, is the right next step.

If your bike is old and repairs would be costly, our guides to budget e-bikes and electric hybrid bikes are a starting point for a replacement.

Frequently asked questions

Why does my e-bike turn on but not assist? Usually an assist level set to zero, a brake lever sensor stuck on, a moved speed sensor magnet or a loose pedal sensor plug.

Can I ride my e-bike without the motor working? Yes, it still pedals like a normal bike, though it will feel heavier. Make sure the brakes work properly before riding.

Can rain stop an e-bike working? E-bikes are built for rain, but water forced into connectors, for example by a pressure washer, can cause faults. Let it dry and check the plugs.

Should I reset my e-bike? Some systems have a reset procedure in the manual. Removing and refitting the battery for a minute is a common first step.

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