E-Bike Diagnostics & Error Codes
An e-bike diagnostic is a systematic test of the battery, controller, motor, sensors, display, and wiring harness that identifies whether a power problem is the pack, the connections, the sensors, or the controller — before you spend money replacing the wrong part.
- Starting at
- $99
- Typical time
- 45 min–1.5 hr
- Warranty
- 90 days on labor
$99 flat — waived entirely if you have me do the repair
Most e-bike "my bike won't turn on" calls are not a dead battery. They're a corroded charge-port pin, a cracked speed-sensor magnet mount, a brake cut-off switch stuck closed, or a connector that vibrated loose on a fire road. Replacing a battery to fix a $12 connector is the single most expensive mistake e-bike owners make, and it happens because the shop that sold the bike is often far away, or won't open the electrical system on a bike it didn't sell.
I start at the wall and work toward the wheel: charger output under load, pack voltage and per-group balance, controller supply and phase continuity, hall sensor signal, PAS and torque sensor output, brake cut-off state, and the display's stored error log. Every step is measured, not guessed. You get a written summary of what I found and what it costs to fix — before I touch anything.
If the diagnosis turns into the repair on the same visit, the diagnostic fee comes off the bill entirely. If it turns out your bike needs a warranty claim through the brand instead, I'll tell you that too and hand you the readings to send them.
Trip fee for this visit
- Zone 1 — San Clemente +FREE
- Zone 2 — Ladera Ranch +$35
- Zone 3 — Irvine +$65
Symptom → cause
What the bike is doing, and what it usually means
| What you notice | What it usually is |
|---|---|
| Bike won't power on at all | Charge port, main fuse, battery contacts, or BMS lockout |
| Powers on, no assist when pedaling | PAS/cadence sensor gap, torque sensor, or brake cut-off stuck closed |
| Cuts out under load or on hills | Weak cell group, loose battery mount contacts, or controller thermal cutback |
| Range dropped by half | Battery capacity loss, drivetrain drag, or tire pressure — tested in that order |
| Motor grinds, whines, or clicks | Hub motor bearings, stripped nylon gears, or a failed clutch |
| Display shows an error code | Code-specific — see the error code reference |
| Assist works, throttle doesn't | Throttle unit, throttle wiring, or controller throttle input |
| Bike shuts off over bumps | Battery mount contacts or a chafed harness wire |
Prices
Diagnostics
Both diagnostic fees are waived in full if you have me do the repair on the same visit.
| E-system diagnosticWaived with repair | $99 |
|---|---|
| Battery health test + written reportWaived with repair | $59 |
| Pre-purchase / second-opinion inspectionUsed-bike buyers — worth every dollar | $89 |
Book service
Need diagnostics?
Takes a minute. You'll hear back within 30 minutes during business hours — and if it's faster to just call, call.
- Free quote before any work starts
- No trip fee in San Clemente, Dana Point or San Juan Cap
- 90 days on all labor
- Nothing gets added to the bill without a call first
FAQ
Before you book
Do you actually work on batteries, motors, and controllers — or just the mechanical stuff?
All of it. This is the main reason to call me instead of a general mobile bike mechanic. Most mobile bike services in Orange County explicitly decline battery, motor, throttle, and controller work, which means a bike with an electrical fault has nowhere local to go. I diagnose and repair charge ports, battery management systems, controllers, displays, throttles, cadence and torque sensors, brake cut-off switches, wiring harnesses, and hub and mid-drive motors — plus everything mechanical.
What brands do you work on?
Every brand. That includes direct-to-consumer bikes with no local dealer — Rad Power, Aventon, Lectric, Ride1Up, Velotric, Heybike, Himiway, Juiced, Super73, Segway — and dealer brands like Specialized Turbo, Trek, Giant, Cannondale, Electra, Gazelle, Tern, Pedego, Blix, Magnum, and Riese & Müller. On the motor side I work on Bosch, Shimano STEPS, Brose, Yamaha, Bafang, Fazua, Mahle, and generic hub systems. One honest caveat: Bosch and some Shimano systems lock firmware and certain diagnostics to authorized dealers. I can do every mechanical and electrical repair on those bikes and I'll tell you upfront on the rare occasion something has to go through a dealer.
My range dropped a lot. Do I need a new battery?
Probably not, and this is the most expensive assumption in e-bike ownership. Lost range has at least five common causes and only one of them is a worn battery: low tire pressure, a dragging brake rotor, a worn or dry chain, colder weather, corroded battery mount contacts, and actual capacity fade all produce the identical symptom. A $59 battery health test measures capacity against the pack's rated watt-hours and checks balance across cell groups, which tells you definitively which it is. That fee is waived if you have me do the repair. A new pack is $400 to $1,200 — it's worth $59 to find out whether you need one.
Is there a warranty on the work?
90 days on all labor. If something I worked on isn't right afterward, I come back and fix it — no trip fee, no argument, in any zone. Parts carry whatever warranty the manufacturer provides and I'll handle the claim paperwork with the brand for you.
What can't you do at my house?
Three things go to the bench rather than the driveway: cell-level battery pack repair (opening a lithium pack in a customer's garage isn't something a careful technician does), full wheel rebuilds and rim replacement, and internal motor rebuilds that need a press. For all three I pick the part or the bike up and bring it back, usually within two to four days. Everything else — including motor removal and reinstall, controller and display replacement, harness repair, brake bleeds, and full tune-ups — happens where your bike is.
Do you need power or water at my house?
No. The van carries its own power, lighting, compressed air, and water. All I need is a flat spot roughly the size of a parking space, within reason of where the bike is. Driveway, street, garage, courtyard, parking lot, or a turnout on a Laguna hillside all work fine.
Do I need to be home the whole time?
Only at the start and the end. I need five minutes with you at the beginning to understand what the bike is doing and to confirm the quote, and five minutes at the end to hand it back and show you what changed. In between you can go to work, take a call, or leave entirely.
My display is showing an error code. What does it mean?
It depends on the system, because every maker numbers its own faults: 21 is a speed sensor fault on a Bafang display but abnormal current on a Rad, and Shimano's codes start with W or E. The free error code lookup has the makers' own tables for Bafang, Bosch, Shimano STEPS, Rad Power Bikes, KT and Segway-Ninebot, with the maker's first step for each. If a code points at the battery or charger, stop charging and riding until it's checked.
Something not answered here? Just ask — I’d rather talk it through than have you guess.