E-Bike Repair Guides & Error Codes

A black wiring harness spread across a plain grey surface, its branches ending in several unplugged round black connectors and a pair of small two-pin plugs with a red wire.
The Minimal-System Method: Find Any E-Bike Fault Without Guessing
Strip the electrical system to the fewest parts that still switch on, then add parts back one at a time to find the fault before you buy anything. Read more...
A black thumb throttle unit with its handlebar clamp, a three-wire pigtail in red, black and green ending in an unplugged three-pin connector, and a slim test probe resting beside it on a plain grey surface.
Throttle Not Working? Test It With a Multimeter in 10 Minutes
Display on, battery full, motor silent? Rule out the three things that imitate a dead throttle, then test it with a multimeter in about ten minutes. Read more...
A close-up of an aluminium brake lever clamped on a black handlebar, with the brake cable and a thin sensor wire ending in a small two-pin connector, against a plain grey background.
The Brake Sensor: The Hidden Cause of "No Power" on E-Bikes
Display on, battery full, throttle dead? A stuck brake cutoff switch can look like a failed controller. The two-minute check and how to test the sensor. Read more...
An opened hub motor on a light wood bench showing copper stator windings, a bundle of red, yellow, green, blue and black wires emerging from the axle, and the aluminium side cover lying beside it.
How to Test E-Bike Hall Sensors (and When It Means a New Motor)
A hall sensor fault is one of the few e-bike problems that feels dramatic and is still cheap to diagnose. The motor shudders, lurches, or refuses to spin, and the... Read more...
A red and black test probe lying on a light wood bench beside a tied bundle of colored wires with stripped copper ends and several unplugged multi-pin connectors.
Five Multimeter Measurements Every E-Bike Owner Should Know
Five two-minute meter checks that separate a dead part from a healthy one: pack voltage at rest, continuity through fuses, the hall sensor 5 V supply, throttle sweep, and brake... Read more...
A set of nine hex keys fanned out on a pale wood bench beside a socket driver with a black grip, a single bolt with its washer, and a short black plastic lever.
Upgrading Controller Amps: What It Costs Your Motor and Battery
Raising a controller's current rating is a torque upgrade, and the extra current has to be delivered by the battery and absorbed by the motor. Here is which component pays... Read more...
A silver aluminium controller on white with a bundle of black cable leads ending in round waterproof plugs, beside a black LCD display clamped to a section of handlebar, its lead finishing in a green five-pin connector.
4 Photos We Need to Confirm a Part Fits Your E-Bike
A model name rarely settles whether a replacement part fits. Four photographs and one measurement do: the display face, its connector, the controller label, and the motor cable where it... Read more...
Three matched drive parts on white: a silver aluminium controller trailing a fan of black connector leads, a black LCD display with its handlebar mount, and a rear hub motor with a coloured wire bundle leaving the axle.
Motor Jerks, Stutters, or Won't Spin: The 36-Combination Fix
A motor that jerks, stutters, or refuses to spin after you fit a replacement controller or a replacement motor is one of the most common problems in e-bike repair, and... Read more...
Waterproof connector crimping kit on grey: rows of small black bullet connectors with teal inserts, a black-and-green crimping plier at centre, plus red, blue, yellow and black heat-shrink tubing in assorted lengths.
Water in the Motor Connector: Inspecting the 9-Pin Plug
An e-bike that jerks, stutters, or loses power from a standstill sends most owners straight to the worst conclusion: the motor is dying. Sometimes it is. But the same symptoms... Read more...
Coiled black e-bike main wiring harness on white: a thick trunk cable enters a moulded black junction block fanning out into four short leads with round black waterproof connectors, one red-insert, one black-insert, plus an orange-insert lead.
Controller, Display, or Both? A Replacement Decision Guide
Controller or display? Spend fifteen minutes proving which part failed: does the screen light, does the throttle drive the motor, and the lit-screen trap. Read more...
A black e-bike LCD display on a white background, shown with its separate three-button control pad marked plus, M and power joined by a black cable, plus two small black rubber handlebar shims; the rectangular screen is unlit
How to Identify Your E-Bike Display Model (and Why It Matters)
Your display's model number and connector decide whether a replacement will work. Where to find the model, the two photos that settle compatibility, the protocol families, and why wattage is... Read more...
A silver finned aluminium e-bike controller lying on a white background, five black cable leads ending in waterproof bullet connectors fanning out from the top edge, three of them coiled and held with yellow ties
E-Bike Cuts Out While Riding: Battery Sag or Controller Failure?
Power vanishing mid-ride is usually misdiagnosed as a dead battery. When it cuts tells you why: load spikes point at voltage sag and the low-voltage cutoff, heat and time point... Read more...
A black LCD e-bike display clamped to handlebar tube on a dark grey background: three round buttons on the left (power, plus, minus), an unlit grey rectangular screen, and a coiled black cable ending in a green five-pin connector
E-Bike Display Won't Light Up: Wiring, Voltage, and When to Replace
A charged battery and a black screen is a narrower fault than a dead bike. Free checks first, one voltage measurement second, and a clear order for replacing the display,... Read more...
A waterproof connector crimping kit on a dark background: rows of black bullet-style connector housings on the left, a ratcheting crimp tool with black and green handles in the centre, and red, blue, yellow and black heat-shrink tubing on the right
E-Bike Won't Turn On: The Complete Power-Chain Checklist
A bike with no display, no lights and no beep is usually a broken link in the power chain, not a dead motor. Walk the chain in order: free checks,... Read more...
A bare rear hub motor seen from the side: its threaded axle and axle nuts protrude from both sides of the motor shell, the spoke flange holes are still empty, and the phase and hall cable is coiled beside it
Hub Motor Sizing: Dropout Width and Axle Diameter Explained
Three measurements decide whether a hub motor fits: dropout width, axle diameter, and wheel diameter with tire width. How to take each one, and the errors that cause returns. Read more...
A bare hub motor: motor shell with empty spoke flanges and its phase and hall cable, not yet laced into a rim
Motor Wheel vs Bare Hub Motor: Which Should You Buy?
A hub motor and a motor wheel are not the same purchase. One arrives already laced into a rim; the other is just the hub. Here is how to tell... Read more...
E-bike right-side thumb throttle assembly, the part behind throttle error codes
Aventon Error Codes: Three Different Systems, One Guide
Aventon splits its error codes across three tables by drive architecture, not by model. Here is which table applies to you, what the hub-drive codes mean, and the replace-the-right-part rule... Read more...
Pedal cadence sensor for an e-bike, one of the signal components involved in sensor-related fault codes
Bafang Display Error Codes and What They Actually Mean
A working table of the common two-digit Bafang fault codes, the two codes that mean something different here than on other systems, and the free checks to run before buying... Read more...
Replacement e-bike main wiring harness with multi-pin connectors, the parts checked first when a display reports a communication or phase fault
APT Display Error Codes: One Table Covers 750C, 850C and More
Seven numbered codes cover APT-style 750C and 850C color displays. What each means, why 02 and 03 start at the connector, and what 08 to 99 mean. Read more...
Replacement e-bike LCD display unit of the type that shows numbered fault codes
SW900 Display Error Codes: The Complete Table and What Each One Means
SW900 codes 0, 1, 4 and 5 are not faults. What error 2 (brake), 3, 6, 7 (motor), 8, 9 and 10-13 mean, and which connector to check before buying... Read more...
E-bike LCD display, the screen that reports KT error codes
KT-LCD Display Error Codes: Complete Table and What to Replace
The KT-LCD3 manual defines five error codes: 01 throttle, 03 motor hall, 04 torque sensor, 05 speed sensor and 06 short circuit. Here is what each one is pointing at,... Read more...
Digital multimeter used to check an e-bike connector after reading an error code
Rad Power Error Codes: The Complete Reference, Updated for 2026
Every error code a Rad Power display can show, grouped by what it is actually telling you to check: the six codes shared across most brands, the codes specific to... Read more...
E-bike controller unit, the part an aftermarket kit replaces
Which Rad Power Models Can Use an Aftermarket Controller Kit?
Rad's earlier RadRover models accept an aftermarket controller kit as-is, several models need modification, and Rover 6, RadWagon 5 and the 500-lumen headlight system are not compatible at all. Here... Read more...
E-bike main wiring harness with phase and hall sensor connectors
E-Bike Controller Wiring Color Codes Explained (Phase + Hall)
What the three thick phase wires and five thin hall wires on an e-bike motor really mean, why you check the controller manual and self-learning first, when matching colour to... Read more...
E-bike LCD display with a five-pin green connector, the plug that decides controller compatibility
Why Your New E-Bike Display Doesn't Work With Your Controller
A replacement display can fit the connector, light up, and still not work. The controller-to-display protocol is the least interchangeable layer of an e-bike. Here are the protocol families, three... Read more...
E-bike LCD display showing rider data, where error codes appear
E-Bike Error Codes 21 Through 30: The Code Family Most Brands Share
Codes 21, 22, 23, 24, 25 and 30 mean nearly the same thing across many e-bike brands, because the controllers share an upstream platform. Here is what each one means,... Read more...
Rear hub motor, 26 inch 750W
Rad Power Bikes After the Bankruptcy: Where to Get Replacement Parts Now
Rad Power filed for Chapter 11 in December 2025. Here is what is actually replaceable on your bike, which models take aftermarket controllers and displays, and what to measure before... Read more...
E-bike 48V controller replacement unit
Your E-Bike Motor Runs By Itself: Stop Riding and Read This
A motor that surges or runs with no input is a dangerous fault with only three possible causes. How to tell which part failed, and what actually fixes it. Read more...
Pedal cadence sensor for e-bikes, the part behind most pedal assist failures
Pedal Assist Not Working But Throttle Works? Try These 5 Fixes First
A throttle that still drives the motor has already proved your battery, controller, motor and main wiring are fine — which narrows a dead pedal assist down to five things... Read more...
Close-up of cylindrical lithium-ion cells standing side by side, joined by nickel strips
How Long Do E-Bike Batteries Really Last (and How to Make Them Last Longer)
Rated range and pack lifespan are two different questions. Here is why rated ranges are so wide, and the habits that decide how long a lithium pack keeps its capacity. Read more...
Riding an E-Bike to High School: Rules, Parking, and Locks
More students are showing up to high school on an e-bike instead of a bus or a car, and most of the questions that come up aren't about the ride itself — they're about what happens before and after it. Is it even legal for a minor to ride one? Where does it go during a seven-hour school day? And how do you keep it from getting stolen in a parking lot full of unlocked bike racks? The rules you actually need to know E-bike laws for minors vary by... Read more...
A hand on a handlebar grip beside the brake lever, with a bell and a round rear-view mirror
Step-Through E-Bikes for Seniors: A Practical Safety Checklist
Nine checks for older riders: standover height, upright position, brakes, throttle protection, tire width, weight, charging habits and class rules. Read more...
Close-up of a wide knobby fat tire resting on sand and gravel
Fat Tire E-Bikes 101: When Do You Actually Need 4-Inch Tires?
What a 4-inch fat tire actually does, when you really need one, when it is about comfort rather than off-roading, and when you don't need it at all. Read more...
Close-up of an e-bike handlebar with a grip, a small thumb lever and a brake lever, a city street blurred behind
Class 1 vs Class 2 vs Class 3 E-Bikes: What the Classes Actually Mean
Class 1, Class 2 and Class 3 e-bikes in plain language: what each class changes about how the bike rides, why it matters, and how to pick one. Read more...