E-bike pedal assist cuts out: causes and fixes

1. Step-by-step plan
2. Assistance cuts out on bumpy roads
3. Display not working
4. Stella: assistance cuts out
5. Giant: assistance cuts out
6. Sparta: assistance cuts out
7. Gazelle: e-bike cuts out
8. Koga: assistance drops out
9. RIH cuts out
10. Batavus: assistance cuts out
11. Qwic: assistance drops out
12. Bosch display cuts out
13. Cortina: bike cuts out
14. Giant / Yamaha motor problems
15. Shimano error codes and fixes
16. Is it the battery? How to have it tested

Does your pedal assist cut out as you are about to set off, or while you are riding? There are several possible causes.

1. Check the battery: this is the most common cause. With a low or nearly empty battery the pedal assist does not work properly. Use the indicator lights on the battery or the display on the handlebar to check the charge level. If the battery is nearly empty, charge it fully.

2. Check the connections: make sure the battery is connected to the bike correctly. Take the battery out and put it back, and listen or feel for the click as the battery locks into place.

3. Check the sensor: some e-bikes have a sensor near the spokes that detects when the wheel is turning. If this sensor is dirty or not working properly, the pedal assist can cut out. Clean the sensor, or go to a specialist to have it repaired.

4. Check the display: if the display is not working, the pedal assist may not work either. Look for error messages on the display, or try resetting the display by holding the on/off button for three seconds.

If these steps do not solve the problem, there may be a deeper fault in the bike's electronics or software.

Step 1: Check the battery

• Always start at the source: the battery. Make sure it is not empty or nearly empty.
• Many batteries have indicator lights that show the charge level. If yours does not, look at the display on your handlebar.
• How you treat the battery decides how long it lasts, so handle it the right way.

Step 2: Check the battery connection

• A common problem is an incomplete connection between the battery and the bike.
• Switch your e-bike off and take the battery out for a moment. Put the battery back carefully and make sure it is held firmly in place.
• Switch your e-bike back on and watch the display for the battery status.
• For older e-bikes: it is normal for battery capacity to fall over the years. If the battery keeps giving trouble, it may be time to replace it. Ask KWS Seuren for advice.

Step 3: Check bikes with a front-wheel motor

• For bikes with a front-wheel motor: check the rotation sensor in the bottom bracket.
• A good way to do this is to hang the bike up and turn the pedals by hand with the e-bike switched on.
• If the front wheel turns unevenly or stutters, there may be a problem with the rotation sensor.
• In some cases you have to give the front wheel a push to get it turning.

Step 4: Check bikes with a mid-drive motor

• For e-bikes with a mid-drive motor: start by checking the display for error messages.
• As soon as you put force on the pedals, the motor should give you an extra push.
• No errors on the display? Then the assistance is most likely working correctly.

Step 5: Check the speed sensor magnet

• An error code on your display can point to a problem with the speed sensor, for example 503 on Bosch, W011 on Shimano or E21 on Bafang.
• The speed sensor works by detecting a small magnet on a spoke. Check that this magnet is positioned correctly and passes the sensor without obstruction.
• If the magnet is out of position, it may need to be adjusted or repaired.

This step-by-step plan is a general guide to tracing faults. If the problem persists or you are unsure, call in a specialist for a detailed inspection and repair. Problems that are specific to one brand are explained below.

If your e-bike cuts out, especially when you ride over bumps, the cause can be a loose battery or a problem with the motor. Sometimes the battery is not held tightly enough, so a jolt shakes it loose and the assistance drops out for a moment.

Battery cuts out while riding

Several faults on an e-bike can affect the electric assistance. A poor connection between the battery and the bike is a common one, often caused by dirt, corrosion or a loose battery. Problems with the display or the controls have the same effect, such as a defect or a communication fault between the display and the motor. Breaks or wear in the wiring, loose connections and faulty sensors such as the rotation sensor can also get in the way of the assistance. So can a faulty motor that is worn or damaged. Finally, some bikes have internal safety mechanisms that switch the assistance off when they detect high speeds or specific faults.

6 possible reasons why the display on your e-bike is not working:

1. Empty or faulty battery

   • The battery is empty or nearly empty.
   • There is a problem with the battery cells or with the BMS (electronics) of the battery.

2. Poor connection between battery and bike

   • Dirt or corrosion on the contact points.
   • The battery has not clicked in properly or is not making good contact with the bike.

3. Display or control problems

   • The display may be faulty or may not be communicating properly with the motor.
   • Error codes on the display that point to specific problems with the electrical system.
   • The battery inside the display is empty or faulty.

4. Wiring and connection problems

   • Breaks, wear or corrosion in the e-bike's wiring.
   • Loose connections between the various electronic components.

5. Software or firmware problems

   • Conflicts between different software versions, or between software and hardware.

6. External causes

   • Water damage from riding in heavy rain or through deep puddles.
   • Physical damage from a fall or a knock, which can damage components.

To find the problem with an e-bike quickly, start with a thorough visual inspection of the bike, paying particular attention to the battery, the display and the wiring. Check that the battery is fully charged and that all electrical connections are clean and firmly attached. Look out for error codes on the display as well, because they point to specific problems.

If you ride an e-bike, you know how much you rely on the display. It shows you essential information such as your speed, the distance you have covered and the range you have left. Like any other part, though, the display on your e-bike can get damaged or fail, and then it has to be replaced.

Does your e-bike display need replacing?

The display on your e-bike may need replacing for several reasons. Common causes are damage from a fall, wear, or internal faults such as moisture getting in. If the display no longer works, or no longer shows essential information correctly, replacement is often the only fix.

Which display fits my e-bike?

When you replace a display, you must choose a model that is compatible with your e-bike. The safest choice is usually a display of the same brand and model as your bike. Manufacturers such as Bosch often offer a range of displays that are compatible with their systems. Universal displays are an option too, but they may need adapters for the cables.

Broken screen: repair or replace?

A faulty display does not always have to be replaced. Sometimes a simple repair is enough, such as replacing an internal battery or fixing a loose connection. Always check your bike's manual first for possible fixes and error messages. If you are not sure, ask a specialist.

What does it cost to replace an e-bike display?

The cost of replacing a display varies. A standard LCD or LED display generally costs less than a more advanced model with extra features such as USB ports or a smartphone holder. On average the price runs from a few tens of euros to a few hundred.

Replacing the display

Replacing the display is usually a simple job:

1. Remove the old display by disconnecting the cables and taking the display off its mount.
2. Fit the new display, connect the cables and fix it in the mount.
3. Check that the new display works correctly.

Every brand uses its own parts, and that sometimes brings problems of its own. Besides the usual problems and fixes, we go into those here for each brand, as far as we know them.

Do you ride a duo bike or tricycle from Huka or Van Raam? These often have a battery from a different brand than the bike suggests. How to find the type is explained on the page about the battery of a duo bike or tricycle.

Having trouble with your Stella e-bike because the pedal assist suddenly stops? Below are the most common causes and what you can check yourself.

Battery problems on a Stella

The battery is often the culprit. Possible situations:

• Charger flashing red: this points to a charging problem.

• Charger stays green: the battery is full, or there is a problem inside the battery (for example a BMS fault or cell imbalance).

• Battery vibrates or shifts while riding: this can make both the assistance and the lights cut out.

• Battery will not charge: check the charger and the charging port for dirt or damage.

• Battery cannot be removed: switch the bike off. If the battery is still stuck, contact a bike mechanic.

• Battery has been dropped: this can cause internal damage that makes the assistance drop out.

• Extreme temperatures: heat or frost can reduce performance. Store the battery somewhere cool in summer and frost-free in winter.

Stella display

The assistance depends on the display. A faulty display can make it cut out.

• Faulty display: the assistance does not work and nothing is shown.

• Replacing the display: necessary to restore the assistance and the functions.

Error codes and faults

A Stella e-bike shows error codes on the display. Common ones are:

• Error 21: check the power supply between the battery and the controller.

• Error 22: points to a fault in the ride assistance.

• Error 30: check the connection between the display and the controller.

Does the error code keep coming back? Have the battery and electronics inspected, or go for a cell replacement (re-celling).

On Giant e-bikes it happens regularly that the display or the pedal assist cuts out. Below are the most common causes and fixes.

Giant battery problems

The battery is your bike's power source. Problems with it often lead to the assistance dropping out.

• Faulty charger: it no longer charges the battery. If the charger is flashing, have it tested or replace it.

• Faulty battery: an imbalance in the cells can stop the battery charging or giving assistance.

• Faulty BMS (Battery Management System): the bike then gives no assistance at all.

• Resetting the battery: this can clear minor software problems. Try it before you have the battery inspected.

Display and electronic systems

• Display problems: does the Giant Twist display cut out, or has the display stopped doing anything? Then it often needs replacing.

• Battery combined with the display: some display problems are caused by the battery. Always check the battery first.

Giant error codes

• Error A5: points to a specific fault that often needs a professional diagnosis. Check the manual or contact an authorised Giant dealer.

• Power assist is not available while one of the indicators (L) is flashing.
• If the LED does not light up during use, check the charge level of the EnergyPak and/or the connections of the EnergyPak. When there is an error message, power assist is not available.

Does your Giant bike keep cutting out, or do you see error messages again and again? Have the battery and electronics professionally tested and re-celled.

Are you stranded because your Sparta e-bike has stopped giving pedal assist? Sparta has a name for quality and reliability, but as with other brands, faults can occur. Below are the most common problems and fixes.

Battery problems

• Reduced capacity: over time the battery holds less charge, which means a shorter range or no charge at all.

• Fix: have the battery re-celled or replace it with a new one.

Motor problems

• Symptoms: the motor cuts out or runs unevenly.

• Causes: technical faults or problems with the cabling.

• Fix: have the motor inspected and, if necessary, repaired by a specialist.

Electronics and display

• Problems: faults in the display or the controls range from small glitches to a system that has shut down completely.

• Fix: often solved with a software update or by replacing faulty parts.

Sensor problems

• Symptoms: the pedal assist does not work, or works unevenly.

• Cause: faulty or wrongly adjusted pedal force sensors.

• Fix: have them replaced or recalibrated by a technician.

Connectivity problems

On modern Sparta models with Bluetooth or wireless functions:

• Problems: the connection drops or does not work properly.

• Fix: update the software or reset the Bluetooth settings.

Battery-related error messages on the ION system:

On Gazelle e-bikes the pedal assist can cut out for several reasons. Sometimes the assistance stops as soon as you set off, sometimes only after a few minutes. Below are the most common causes and what you can check yourself.

Common causes

• A worn or poorly performing battery.

• A faulty pedal force sensor or speed sensor.

• Cabling that is loose or damaged.

• Problems with the display or the controller.

What you can check yourself (5-minute check)

1. Fit the battery and clean the contacts: take the battery out of its holder and check that the contacts are clean. Clean them with a dry cloth if necessary.

2. Speed sensor magnet: check that the magnet at the wheel passes the sensor properly and has not shifted.

3. Cabling: look for cables that are hanging loose, kinked or damaged.

4. Display: is it clicked firmly into place, and does it respond correctly when you switch it on?

Resetting the display on your Gazelle Bosch e-bike

Has the display on your Gazelle with a Bosch drive system cut out? A software fault may be the cause. You can clear it by resetting the display. Switch the display on and hold the reset and i buttons at the same time for at least three seconds. This takes you to the settings menu. Scroll through all the available display options, choose the one you want and hold the reset button until the screen is back at zero.

Incorrect speed on the display

Does your display show a speed of 0 km/h while you are riding? That can be a sign that the sensor magnet is not positioned correctly. To deal with this, move the magnet on the rear wheel so that it sits closer to the sensor. Keep the distance between the magnet and the sensor as small as possible for an accurate speed reading.

Error codes: Gazelle Panasonic system

Error codes: Gazelle Innergy system

Error messages that have to do with the battery of a Gazelle Innergy:

Gazelle Innergy problems

Error codes that have to do with the motor of a Gazelle Innergy:

Is the pedal assist on your Koga e-bike dropping out? Koga bikes are fitted with different drive systems, such as Bosch, Shimano and the Ion line. Battery problems are less common on a Koga, but faults can still occur.

Common complaints

• Loss of pedal assist while riding.

• Display not working as it should: no information, or the wrong information.

• Limited range from the battery: the bike covers fewer kilometres than normal.

Note: the exact cause and fix differ per type of drive system. Spot complaints in good time and you avoid bigger problems.

Koga ION: error codes

On the Koga ION line, various error codes can appear on the display. These codes show where the problem lies and help with the diagnosis.

Does your Koga e-bike keep cutting out, or do error codes appear that you cannot clear yourself? Then have the battery and electronics inspected and re-celled, so that the bike runs reliably again.

RIH e-bikes are known for their reliability, but faults can occur on this brand too. Below are the most common problems and fixes.

Extra point to watch: removing a RIH battery

Sometimes the RIH battery is stuck and will not come out in the normal way. Never try to lever it out by force, because that causes damage. Have it checked by a mechanic or specialist. Removing a RIH battery.

Is the pedal assist on your Batavus e-bike cutting out? There are several possible causes, from a worn battery to problems with the motor, a sensor or the electronics. Even smaller things, such as loose wiring, can cause faults.

Battery and compatibility

• Like all batteries, Batavus batteries lose capacity over time.

• When the battery reads empty, there is often some residual capacity left, enough to keep the lights working for example.

• Compatibility:

  • With systems such as Bosch, E-motion or Shimano you can often use different batteries.

  • On Batavus ION the batteries are protected and not interchangeable.

Error codes: Batavus Ion system

The Batavus ION system shows fault codes on the display. Each error code points to a specific problem.

Having trouble with the assistance on your Qwic bike? Here you can read how to fix it and how to prevent it.

Qwic battery problems, assistance drops out while riding: First check that your e-bike battery is fitted correctly. If that seems to be in order, the battery charge may be below 10 to 20%. At a capacity of less than 10 to 20% the electric assistance switches off to protect the battery against deep discharge. This mainly happens when a lot of power is being demanded.

If you are still on the road, try switching the battery back on. Select a lower assistance level on the display, so that you can reach your destination with electric assistance. Charge the battery as soon as possible once you arrive.

Qwic display will not switch on

The problem can be in the battery, but also in the connections between the display and the controller, or between the motor and the controller. Check these first before you start looking at the battery.

Qwic fault codes

Your bike has a self-diagnosis function so that any faults can be identified and fixed quickly. Faults are shown with a fault symbol and a code on the display, in the place where the selection field normally is. Some faults you can fix yourself.

Newer models

Fault codes for MD11, MD11 Speed, MN380, MA11 Speed:

• Fault 48 (no speed signal): check that the small magnet in the rear wheel passes the speed sensor on the frame correctly. The magnet may have come loose.
• Fault 65, 66 or 67 (battery capacity low): make sure the battery is fully charged. Charge the battery if necessary.

Fault codes for RD11, RD11 Speed:

• Fault 64, 66 or 67 (battery voltage too low): check that the battery is properly charged. Charge the battery if necessary.
• Fault 80 (system temperature): the drive has overheated. Let the bike cool down. Contact your dealer if the problem keeps coming back.
• Fault 116 x (brake sensor): this fault can occur if the brake is squeezed while the display is starting up. If the brake was not applied, contact the dealer.

Older models

QWIC e-bikes with an H501 console from 2016 or earlier show the following error codes.

Does your Bosch bike computer cut out while you are riding? When an e-bike with a Bosch system has trouble with its assistance, there are several possible causes. A thorough check of the battery and the electrical circuit often tells you more.

The table below gives an overview of Bosch error codes with the problem and the fix that go with each one:

To prevent or resolve these problems, have the bike serviced and inspected regularly by a certified dealer or specialist. At KWS Seuren we can inspect the battery in detail and, if necessary, re-cell it. Software and sensor faults on the bike itself are a job for your dealer, because we only work on the battery and the charger.

Does your Cortina e-bike suddenly stop assisting while you are out riding? Below are the most common causes and what you can check yourself.

Quick checks

• Check that the Ecomo battery is seated firmly in the lock and cannot move in the carrier.

• See whether the battery is fully charged.

• Does the charger no longer charge the battery all the way? Then the problem may lie in the charger or the battery.

• Rule out problems by temporarily swapping components where possible, or by testing with another battery or charger.

• On the Cortina Ecomo display you can set the capacity: check that it matches the capacity of your battery.

Assistance drops out while riding

• Always check first that the battery is fitted correctly.

• Is the battery charge below 10 to 20%? Then the assistance switches off automatically to protect the battery against deep discharge.

  • On a 24V battery this happens at around 21V.

  • On a 36V battery the assistance switches off below 30V.

Cortina Ecomo battery cuts out

A common problem on the Cortina Ecomo:

• The battery no longer charges fully.

• The bike cuts out suddenly, especially when the battery is nearly empty.

Possible causes:

• Worn battery cells.

• Faulty BMS (Battery Management System).

• Condensation or moisture in the battery: this can cause faults.

Yamaha e-bikes are known for their reliability and efficiency. Even so, problems with the motor, the sensor or the battery sometimes come up. Here are some common problems and their fixes.

Problem: the assistance level cannot be changed

• Fix: if you cannot change the assistance level, dust or dirt under the buttons of the display may be the cause. Open the display carefully and clean the buttons. After cleaning you should be able to adjust the assistance level again.

Problem: sensor alignment

• Fix: check the sensors at the crank and the rear hub. Make sure they are clean and correctly positioned. If they are not aligned properly or are obstructed, adjust them. If in doubt, contact an authorised dealer or repairer.

Problem: noise or vibration from the motor

• Fix: check whether there are loose parts in the drivetrain or the motor housing. Tighten them if necessary. Make sure the chain is well lubricated too, which helps to reduce noise.

Yamaha/Haibike error codes and fixes

Twisted spoke magnet

• Error codes: SPD SNSR/CHK MAGNET
• Cause: the spoke magnet on the rear wheel is not positioned correctly.
• Fix: put the magnet back in the correct position. If the problem persists, have the wiring and the plug connection checked by your dealer.

Torque sensor errors

• Error codes: 31 to 37
• Fix: these errors point to a problem with the torque sensor and can often be cleared easily by a visit to your Winora/Haibike dealer.

Crank sensor problems

• Error codes: 38 and 39
• Fix: unless the problem is caused by a dirty or misaligned magnet, it is best to consult a dealer you trust. They can identify the error code with a Yamaha diagnostic tool and clear the error.

Shimano e-bikes, including the popular EP8 and the STEPS E8000, E7000, E6100 and E5000 motors, are known for their reliability. As with all technology, though, error codes sometimes appear. Below is an overview of the most common error codes and their fixes.

Error code W103, W106, W013 or E012: problem with the torque sensor

• Cause: the torque sensor may not have been fully initialised.
• Limitation while the error is shown: less assistance than usual, or none at all.
• Fix: take your feet off the pedals, press the on/off button on the battery and restart the system. Important: put no pressure on the pedals while switching on and off. If this does not help, try the general steps for these codes further down this section.

Error code W101, W011 or E014: problem with the riding speed sensor

• Cause: the riding speed is not being detected.
• Limitation: the maximum speed at which assistance is given may be lower than usual.
• Fix: check that the speed sensor is installed correctly and that the spoke magnet is in the right position. The distance from the sensor on the chainstay to the spoke magnet must be between 3 and 17 mm.

Error code W100 or W010: problem with the motor temperature

• Cause: the temperature of the motor is higher than normal.
• Limitation: less assistance than usual.
• Fix: take a break and wait until the temperature of the motor has dropped. Do not use the assistance function until then.

Error code W20: problem with the battery temperature

• Cause: the battery temperature is outside the operating range.
• Limitation: the system does not start up.
• Fix: if the temperature is above the range, keep the battery in a cool place out of direct sunlight until the internal temperature has dropped. If the temperature is too low, keep the battery indoors or in a warm place until the temperature is within the permitted range.

Error code E10: system error

• Cause and limitation: a system error has occurred, no assistance when pedalling.
• Fix: restart the system. If this does not solve the problem, visit the dealer.

Error code E20: communication error

• Cause: communication error between the battery and the motor.
• Limitation: no assistance when pedalling.
• Fix: check that all cables between the battery and the motor are connected correctly and are not damaged. Swap the battery.

Error code W012: problem with the crank

• Cause: the crank is fitted incorrectly or is at the wrong angle to the drive unit.
• Fix: install the crank correctly and restart the system. If there is no improvement, visit the dealer.

General fixes for error codes W013, W103, W106 and E012

• Step 1: switch the e-bike off for 10 seconds and then on again, without putting any pressure on the pedal. It is best to get off the e-bike completely.
• Step 2: if step 1 does not work, turn the crank backwards two or three times and repeat step 1.
• Step 3: the torque sensor can also be initialised while riding. Go for a short ride with the motor on.
• Step 4: if the steps above do not help, incorrectly adjusted chain tension may be the problem. Check and adjust the chain tension of your e-bike.
• Step 5: if the previous steps do not help, try the following trick: clamp the e-bike in a workstand, or raise it on a safe bike stand, so that the rear wheel and the cranks can turn freely. Switch the e-bike off and on again. Let the cranks turn until the e-bike reaches a target speed of between 10 and 20 km/h. Stop the cranks in one position for 2 seconds, then accelerate again and let them spin freely. Repeat these steps several times, stopping the cranks in the same position each time. If there is no improvement, repeat the procedure and stop the cranks in a different position.

Shimano error codes

Have you been through the steps above and is the assistance still dropping out? Then the battery is the first suspect. A battery with worn cells delivers enough voltage to switch the display on, but sags as soon as the motor draws current. On the bike you notice this when you set off, in a headwind or on a hill.

Register your battery through the product page for your model, in our overview of batteries for e-bikes. The bike stays at home; we only need the battery and the charger. Outside the Netherlands? Contact us first and we will tell you how to send it. We carry out an intake test and measure the capacity. After that you receive a proposal with a price: a repair of your e-bike battery if a part is faulty, or a cell replacement (re-celling) if the cells are worn out.

A cell replacement starts at €300. If you decline our proposal, you pay the €95 inspection fee. The prices for each option are on the page what does an e-bike battery cost, and you can read how long it takes on the lead time page.