E-bike Repair and Maintenance: How to Diagnose and Solve Common Electric Bike Problems

While electric bikes are pretty similar to traditional bicycles in terms of form and function, they do require a few extra points of care to maintain them in tip-top shape and to avoid some big bills. Those that ride their eMTB a lot and push hard will find themselves with the most breakages, and e-bikes are considerably more complex than their analog cousins. You are going to break things, whether you like it or not. Thankfully most e-bikes, and specifically the batteries and motors, have a two or three year warranty and are much more reliable today than they used to be.

Battery care and storage

The battery is one of the most expensive parts of your ebike. Replacement batteries can run you about $1,000+, and without a battery, an e-bike is just a very heavy bike, so it pays to keep the battery in good shape. Most electric bikes these days use lithium-ion batteries, and while they’re pretty robust, there are definitely some do’s and don’ts to keep your battery in the best possible condition.

The first is to consider the conditions in which you keep and charge the bike. Shimano for example recommends a 0 to 40ºC safe temperature range for charging and -10º to 50ºC for operating. Those quoted temperatures are of course extremes, and while a battery may operate on the extreme end, it’s better for the life of the battery for it to be kept somewhere in the middle which is about 20ºC or room temperature. If the bike is stored somewhere cold like an unheated garage in the winter it could be a good idea to remove the battery and bring it indoors, or consider keeping the bike somewhere warmer in the winter months. 

On the topic of storage, since the bike is electric it should go without saying that water ingress is a potential problem. Storing the bike inside is the best way to keep the bike in the best possible condition. No electric or non-electric bike for that matter should ever be stored outside, even covered, since humidity, rain, etc. can cause corrosion, seals can dry out, and it’s generally bad news for the bike. Add in electric components and outdoor storage is a recipe for bad results.

[Editor’s note: Consumer Reports says to avoid charging an electric bike overnight or unattended. Also be sure to use the charger provided by the manufacturer, and you should stop using a battery that changes shape, emits any sort of odor, or becomes excessively hot to the touch.]

While we’re talking about battery best practices, again you’ll want to use the same practices that you’ll use with any li-ion battery. You don’t need to charge to 100% full every single time; the batteries work best between 20% and 80% charge, and doing a big charge from 20-80% is preferable to lots of small charges. For example if you know your commute uses 10% battery each way don’t charge your bike every day when you’ve only used 20%, charge it almost fully every 4 or 5 days when you hit roughly 20%. It’s best to charge the bike just before you plan to ride, rather than right after you’ve finished a ride. The University of Michigan has some good additional information about maximizing the life of lithium ion batteries here.

Draining the battery to 0% is safe every now and then, but don’t leave it that way — recharge it as soon as you can. Likewise, don’t frequently charge to 100% if you don’t need the full range, though it’s helpful to do this occasionally to calibrate the cells. If the bike is being put into storage it’s best to keep it around 40-60% charge and check it every now and then.

For bikes with a magnetic charge port, be sure to inspect it regularly for small metallic items stuck to the port or the charger. Always inspect the charger cable before charging the bike since something like a staple could arc across the battery terminals and render it useless.

What to do when your e-bike breaks

Most e-bikes will experience electrical or electronic issues at some point, some of which can be easy to solve, others less so. I’ll start by saying that often the best course of action (but not necessarily the first) is to contact your local bike shop. More often than not, they will want to see the bike in person, since issues can be difficult to explain over the phone/email. For the most part, diagnosis of e-bike errors requires proprietary software which is often only available to dealers. That means it’s often nigh on impossible to diagnose and/or fix e-bike problems involving the electronics.

However, one of the simplest things you can do to try to fix an error is to simply turn the bike off and on again. This should be the first thing you try after recording whatever the error code was.

It’s worth noting also that most shops have an agreement with their brands whereby they are contractually obliged to take care of warranty issues for the brands they carry, whether or not that bike or part was purchased through them. This means you do not necessarily need to go back to the shop where you purchased the bike — you should be able to use any shop that carries your brand, which is the benefit of a dealer network.

This does not always mean they will do the work for free — you may be charged labor — however some brands like Specialized do credit their dealers for labor. In most straight-forward warranty cases, you will not and should not be charged labor by the shop for replacement of warranty parts on a Specialized bike, regardless of where you bought the bike. Some shops will offer free labor to their customers for a certain time period, some might not, and this is down to the discretion of the shop, however I encourage you to read up on the warranty policy for your particular brand. Some brands may offer a transferable warranty which is good to know if you are thinking of purchasing a used e-bike.

Also worth noting is that the warranty on each part of the bike is different depending on the brand. For example, on a Trek bike the frame warranty is held by Trek, the motor warranty is through Bosch, the fork is Rockshox or Fox, and the drivetrain is Shimano or SRAM. While you can still go to almost any shop for your warranty, the policy and the period is likely to be different depending on the brand. For some brands like Santa Cruz frames and Reserve wheels you can submit a warranty claim online yourself.

Electric bikes come with the risk of electric shock. If disassembling or working on your electric bike at home, ensure you disconnect the battery at a minimum to prevent the risk of shock.

Motor-Specific issues

An e-bike rides much the same as a regular bike, though one obvious difference is that it puts out a lot more power. And with great power comes great responsibility.

The first and biggest thing is to use your gears like you would a normal bike to ensure a long life for the motor. Quite often people rely on the torque of the motor to get them going and tend to sit in a hard gear letting the motor do all the work. This is bad for a number of reasons; it’s a less efficient gear to be in, draining battery power faster, and it puts more strain on the motor. Motors drive the main drive sprocket via a belt or often a plastic cog inside the motor housing, which over time can wear, become noisy and/or break. Just because you can rely on the motor for low down torque doesn’t mean you should.

Electric bike motors are tuned to be most efficient at the same cadence as the human body; this is what helps them feel natural and easy to ride. A cadence of 75-100rpm is the sweet spot for motor efficiency – riding within this range will use less juice from the battery since the motor isn’t struggling to keep up. Remember, if your legs don’t like pushing that hard a gear, neither does your motor. Many e-bike handlebar computers can be customized to display cadence on screen so it’s easier to see your cadence and stay in this efficient zone.

Most e-bike motors these days are pretty well sorted however as with anything, they can break. Like any electronic device, they can randomly die, sometimes as a result of a software issue, sometimes water ingress, sometimes maybe just a bad solder joint. Since they’re sealed units where the warranty is void if opened, there’s often no real way of knowing what the problem is. If your bike is not covered under warranty, then a new motor can cost around $1000 – one of the many reasons I suggest buying brand new from a reputable brand.

For a little while the early Shimano EP8 motors were getting the E010 error code that meant that the motor was just ‘dead,’ though this issue seems to have been remedied.

Specialized Brose motors on the full-power turbo bikes had problems with the drive belts stripping, which is characterized by a high-pitched, whining sound when pedaling unassisted. Specialized released a firmware updates to address the problem and presumably upgraded the belts to prevent this from happening.

Many or most motors will develop creaks and cracking noises when pedalling. This is often simply friction and/or grit in between the motor and the mounting points on the frame. One of the first things to do is to check the motor-mounting bolt torques; you can likely find these values listed on the manufacturer’s website, depending on the bike. If the motor mounting bolts are torqued correctly, then the next step would be to remove the bolts, clean and grease the interface between motor/frame/bolt and reassemble to spec. Again it’s worth referring to the manufacturer’s user manual/documentation to make sure you know the proper steps. It’s worth being aware that some manufacturers recommend using new bolts every time.

E-bike battery errors

Sometimes an e-bike will throw a battery error. This can be because the bike can’t find the battery, or it could be that there’s a problem with the battery. The first thing to do is to check that the battery is securely connected to the bike and that the terminals are clean and dry and connect securely. See the section below for troubleshooting a bad connection.

If the battery is properly connected and good, there is a possibility that the battery itself could be the issue. Start by inspecting the battery – has it been dropped? Is there damage to the casing? If there is visible damage to the casing, remove the battery from the bike immediately, preferably put it somewhere outside of your house if possible in a metal container and/or in sand and contact your LBS for next steps. A battery that goes into thermal runaway is extremely dangerous.

If the battery casing appears to be intact, there is a possibility that the battery has encountered some sort of internal error. This can happen – possibly there’s a loose connection inside, or the firmware has corrupted itself. Often the battery firmware can be updated/rewritten and this may solve the problem, but this does require a trip to the LBS. If that doesn’t solve the problem, it will likely be a warranty case and a replacement battery, since batteries are not user-serviceable. This does happen from time to time, but instances of faulty batteries are much lower than they used to be.

E-bike won’t turn on

If the bike doesn’t turn on at all, this can often be something as simple as a loose connection. The simplest thing you can do here is check all visible wire connections and ensure they are fully plugged in. In the case of Shimano e-bikes, wires often and easily come unplugged from the rear of the head unit/display on the handlebars – ask your LBS if they have a spare Di2 wire tool to make unplugging/plugging these in easier. In the case of Specialized bikes, if the magnetic Rosenberger battery plug is not properly seated the bike may not power on. Ensure the plug is properly seated but do not force it.

The same goes for any e-bike with a battery that is disconnected for charging or can be removed at all – for example a battery that drops out of the frame. Remove the battery and check that none of the terminals on the battery or the frame are bent/misaligned and ensure they are clean. Electrical contact cleaner can be used to clean the battery contacts to ensure a good connection. Make sure the battery seats properly and is not loose. A loose connection might cause the battery to not power on or produce a sporadic connection. The battery lock/latch may need adjusting for a better fit. Again refer to the documentation for your particular bike if it’s not clear how to adjust this or contact your LBS.

Other electrical and electronic Issues

Electric bikes are comprised of many small parts and ancillary components, and occasionally these will fail. There are a few common problems that might arise across most brands, some of which can be easy to fix. I’ll start by saying that most e-bikes have some way of telling you what kind of error they’re experiencing, so you’re not always in the dark. If you experience an error, the display or remote will give some kind of code, whether it’s text like “W101” or a combination of flashing lights.

That code will not always stick around, so I would recommend taking a photo of the error so you have something to go on later. Additionally most e-bikes have an accompanying Smartphone App that has some level of error diagnosis. For example the Specialized Mission Control app will report the error, give a basic description of the error, and any steps the owner can take to fix it, or let them know if they need to visit a dealer.

Speed-sensor error

All e-bikes have some form of speed sensor, usually built into the rear wheel or brake rotor. An error with the speed sensor will often come in the form of some assist when the bike is turned on followed by it suddenly cutting the assist and not reading any speed. The system will stay on but not give any assist. On some e-bikes the speed sensor is located on the chainstay with a magnet attached to the spokes, similar to a speed sensor on a cycle computer. The magnet can come out of alignment with the sensor, so the first thing is to check that the magnet and sensor are aligned and clean.

On many high-end ebikes the speed sensor magnet is now built into the rear brake rotor or lockring which means it cannot come out of alignment, but that means it can get covered in brake dust and give a bad reading. It’s worth checking that the magnet is clean, or if you just built a new bike that you actually have a magnet on there at all. If these don’t fix the issue, the sensor itself could be the problem, in which case you’ll need to contact a dealer.

Error W013

A Shimano-specific error is error W013 or E013. This is an error in the calibration of the torque sensor when turning the bike on. The sensor calibrates itself each time the bike is turned on, and if it gets a reading it’s not expecting, this causes an error. Typically this is when the bike is turned on with a rider on the bike and a foot on one pedal. This error is easily fixed by getting off the bike and turning the bike off and on again. This error should only occur on older E8000 series motors, not the newer EP8, and it can be a good habit to always turn the bike on while standing beside it, rather than sitting on it.

Environment-related errors

Other common errors include temperature-related and water-related errors. Occasionally components may get too hot or cold, and if your bike tells you this is the case, you’re obviously going to know whether either too hot or too cold was the problem. Simply take the bike home or if you can where you are, let it warm up or cool down. Or, try switching it into a lower power setting if it’s overheating. Just as humans can get too cold or hot, so can motors.

If water ingress is the problem, take apart the connections you can see or easily get to, and dry them out with a towel or some compressed air. Ensure your battery is disconnected first to prevent risk of electric shock. Typically Specialized e-bikes can get water ingress into the battery charge port since it’s fairly exposed near the crank area. Dielectric grease can be used to waterproof connections – a small amount around the seal is all it needs. Ensure the charge port cover is securely fitted again before riding.

Head unit battery

Many e-bike head units, screens, displays, etc. will have a small coin cell type battery in them to keep them running even when the bike is off and/or the battery is removed. They do last quite some time — up to a year in many cases — however they can get low, which may produce an error. See error 6 on the Specialized TCU error diagram above. This may also give some sort of text error such as “lo batt” for example on the Specialized TCD (Turbo Connect Display). These batteries are typically pretty easy to swap out and require a small screwdriver or a T10 Torx key and a pair of tweezers.

Maintenance schedules

As far as maintenance schedules go, there really isn’t a schedule for electronic components. Most are not designed to have a specific service life so they shouldn’t break, even though we know they do. Speed sensors do not have a specific lifespan, and motor bearings are usually not designed to be replaced and are typically a warranty motor replacement where the old motor is often refurbished and sent out as a replacement down the line.

For regular bike components, there is no specific maintenance schedule, just like an analog bike. Yes you will go through drivetrain and brake components faster than with an analog bike since there is more power and weight. So, get yourself a chain checker if you don’t have one. Learn how to check brake pads, and maybe carry some spares. The rate at which you’ll need to repair and replace parts depends on many things like rider weight, where you ride, how you ride, and how much you ride.

That said, you should expect to go through consumable parts at roughly twice the rate of your regular bike. That include tires, chains, cassettes, brake pads, rotors, and bearings. Suspension should be serviced according to the factory recommended interval – usually 50 hours for an air can/lowers service and 200 hours for a full tear down.

Summary

This guide is not meant to be exhaustive, but should provide a good starting point. One of the main takeaways is that while there are certain errors that can be solved at home relatively easily, e-bikes are definitely not as home-serviceable as a non-electric bike and often require a trip to the dealer to figure out problems. Quite often it’s not entirely clear where an error may be coming from, particularly when the bike doesn’t turn on and therefore cannot be digitally diagnosed. Cases such as this often require parts to be thrown at them until something works, which obviously is difficult when you don’t have several bikes worth of spare parts like a decent e-bike dealer should.

When diagnosing problems, make sure to approach them methodically and make note of any repeating factors — for example, an error happens when I do this with the bike — and record any error codes that the bike displays. Contacting a dealer is usually the best thing to do, and often they can provide more specific information on your model of bike, sometimes diagnosing things over phone or email. Bike shops are there to help, so don’t be afraid to get in touch.