Short answer: Aventon keeps three separate code tables (Hub Drive, ACU Hub Drive and Mid Drive), so confirm which system your bike has before you look a number up. On hub-drive bikes, E21 to E30 cover current, the throttle, motor phase and hall, the brake sensor, overheating, motor lock, low and over voltage, and display communication. Whatever the code, reseat the plugs on that circuit before you buy a part; the exception is a code that names the battery (Upway lists E44 that way), which goes to Aventon.
Aventon does not publish one error-code table. It publishes three, and they are split by drive architecture rather than by bike name or model year. Look a code up in the wrong table and you can spend money on a part that was never at fault.
Here is how the three are organized, the hub-drive codes you are most likely to meet, and the one decision in the official documents that saves the most money.
Quick reference: Aventon hub-drive codes
Unplug, reseat and inspect connectors with the bike switched off and the battery removed. Reconnect the battery and switch on only for the steps that need power, such as reading the code, a voltage reading, a reset or testing the throttle and pedal assist, and switch off again before you touch the next plug. The first check for each code is free; the detail for each one is further down this page.
| Code | What it points to | Check first | Source |
|---|---|---|---|
| E21 | Current above what the controller permits | Switch off and let the bike cool, then look for chafed, dirty or loose motor and controller cabling | Pace 500 manual (2018); third-party: Electric Kicks |
| E22 | Throttle | Make sure the throttle returns to rest and nothing is jammed against it; look for a nicked or crushed throttle cable | Pace 500 manual (2018) |
| E23 | Motor phase | Clean the motor connector and seat it firmly | Pace 500 manual (2018) |
| E24 | Motor hall sensor | Same first step as E23: clean and reseat the motor connector | Pace 500 manual (2018) |
| E25 | Brake sensor, or a lever held at power-up | Restart with your hands off the levers; if it stays, check the sensor gap and the lever assembly | Pace 500 manual (2018) |
| E26 | Overheat | Stop and let the system cool; report it if it appears on flat ground | Third-party: Upway, Electric Kicks |
| E27 | Motor lock | Check the rear wheel for anything jammed in it, clear it and restart | Third-party: Upway, Electric Kicks |
| E28 | Low voltage | Charge to completion and try again | Third-party: Upway, Electric Kicks |
| E29 | Over voltage | Confirm the battery and charger are the ones the bike shipped with | Third-party: Upway, Electric Kicks |
| E30 | Controller-to-display communication | Inspect every cable between the two before replacing anything | Pace 500 manual (2018) |
| E31 | Battery communication (CAN systems) | Follow Aventon's own E31 steps for your model; we have not found a general first check we can confirm | Third-party: Upway, Electric Kicks |
| E41, E42, E44 | Electric Kicks lists controller (E41), motor (E42) and torque sensor (E44); Upway's list gives motor (E41), torque sensor (E42) and battery (E44) | Confirm the meaning on Aventon's own page for your model. If your code names the battery (Upway's E44), stop using it and contact Aventon; otherwise repair the connection before replacing any part | Third-party, and they disagree: Electric Kicks, Upway |
Meanings are summarized in our own words. The Source column shows where each row comes from: the codes printed in the 2018 Pace 500 owner's manual, or, for the newer codes, the independent guides from Upway and Electric Kicks, which are third-party summaries rather than Aventon documents, so check Aventon's help center for your model too; for E41, E42 and E44 the two guides do not agree. Codes for the other brands we cover, with source links, are on our e-bike error code lookup.
Three tables, split by architecture
The three sections are Hub Drive, ACU Hub Drive, and Mid Drive. ACU refers to bikes built around a smart control unit with connectivity hardware on board, and those carry codes the other two platforms do not have. Mid-drive bikes reuse most of the hub-drive numbering but add their own entries for the display and electronic shifting.
The format is unusually good for riders: one article per code, each with a diagnostic flow chart published as a PDF. That is closer to a service manual than most brands put in public.
The hub-drive codes you are most likely to see
E21, current error. Aventon's Pace 500 manual calls it a current error and points at the cable that joins the rear hub motor to the rest of the system; Electric Kicks adds that it can happen on long climbs at maximum assist, when the controller may cut power briefly to protect itself. Switch off and let the bike cool, then inspect motor and controller cabling for chafing, dirt, or a loose plug. If it comes back on flat ground after the plugs are clean and the bike has cooled, the motor or controller is the suspect; ask Aventon before buying one.
E22, throttle error. Check that the throttle returns to rest cleanly and that nothing is jammed against it, then look for a nicked or crushed section of throttle cable. If neither turns anything up, the throttle assembly is the part to replace.
E23 and E24, motor phase and motor hall. The current documentation answers these with a flow chart rather than written steps. The older published guidance was to clean the motor connector and seat it firmly, and to contact support if the code survives that.
E25, brake sensor. Holding a brake lever while the bike powers up will trigger this on its own, and a restart clears it. If it persists, the sensor gap needs adjusting or the lever assembly needs replacing.
E26 and E27, overheat and motor lock. E26 asks you to stop and let the system cool, and it usually clears itself; if it appears on flat ground, that is worth reporting. E27 is motor lock protection: the system has detected a locked motor or an excessive load. One cause is something stopping the rear wheel from turning, so switch off, check that the wheel turns freely, clear anything jammed and restart. If the wheel spins freely and the code stays, ask Aventon before buying a part.
E28 and E29, low and over voltage. For E28, charge to completion and try again. If it continues, the pack voltage needs measuring at a dealer, and a pack that will not reach its rated figure when charged is the part to replace. E29 points the other way, and the first thing to confirm is that the battery and charger are the ones the bike shipped with.
E30, E31, E41, E42 and E44. E30 is a controller-to-display communication failure: inspect every cable between the two, and if that changes nothing, the documented replacement order is display, then controller, then harness. E31 is battery communication on CAN systems. For E41, E42 and E44 the two published lists we found disagree: Electric Kicks names the controller (E41), the motor (E42) and the torque sensor (E44), while Upway names the motor (E41), the torque sensor (E42) and the battery (E44). Neither is an Aventon document, so confirm what your model's code names on Aventon's own page before buying a part. What you can check for free depends on which list is right. Electric Kicks starts, with the bike turned off, with the accessible connections for that circuit: the display cable and harness for E41, the motor and its harness for E42, the torque sensor and its cable for E44 (take the battery off first, as above). Upway treats E44 as an internal battery fault and says to stop using the battery and seek professional service, so do not test a battery yourself on that reading. If the bike or battery shows damage, heat, smoke or a burning smell, stop using it and contact Aventon.
The table also covers battery, lighting and charger-mismatch entries, plus W-prefixed warnings for throttle, thermal limits, motor lock, and out-of-date firmware. ACU adds control-unit communication, battery lock failures, geofencing, and connectivity warnings. Mid-drive adds a display fault code and electronic shifting entries.
About Error 04
People search for this one constantly, so it is worth being direct: we looked for an Aventon Error 04 across all three official tables and did not find it. If a two-digit 04 is on your screen, it is more likely coming from a display sourced elsewhere than from the Aventon code set. Two-digit tables from other display families do use 04, which is a good reason to identify your display before trusting any table.
The decision that saves the most money
This part is worth memorizing, and it applies beyond one brand. When pedal assist and the throttle are both dead, the shared component is the controller, and that is what the official guidance replaces. When only one of the two is dead, the fault is in that input: a dead throttle with working pedal assist means the throttle, and dead pedal assist with a working throttle means the cadence or torque sensor. Torque-sensor bikes should have the factory reset procedure run first, since a sensor that only needs recalibrating looks exactly like a failed one.
When the checks do narrow it to one part, compare connectors against our throttles and sensors or any replacement controller before ordering, rather than going by the name on the bike.
Common questions
Is there an Aventon Error 04?
We did not find one in any of Aventon's three official tables. A two-digit 04 is more likely coming from a display sourced elsewhere, so identify your display before trusting any table.
The throttle and pedal assist are both dead. Which part is it?
When both are dead, the shared component is the controller, and that is what the official guidance replaces. When only one is dead, the fault is in that input: the throttle, or the cadence or torque sensor. On torque-sensor bikes run the factory reset procedure first.
Does an Aventon code mean a part has failed?
No. A code tells you which subsystem is complaining, not which part has failed. Switch the bike off, work through the connectors and cabling on that circuit, and use the minimal-system method if you still cannot tell. The exception is a code that names the battery, such as E44 on Upway's list: stop using that battery and contact Aventon.
Two honest limits
These meanings come from Aventon's own manual and from independent guides (Upway, Electric Kicks), not from us, and they can change with firmware. If a printed manual came with your bike, that manual wins. And a code tells you which subsystem is complaining, never which part has failed, which is why every entry above starts with connectors and cabling before any replacement, except a suspected battery fault, which goes to Aventon.
If your bike is not an Aventon, the numbering may still look familiar, because a family of brands share the same 21 through 30 block. We covered that overlap in the code family most brands share. For the wiring behind E23 and E24, see controller wiring color codes. And if you are chasing a dead pedal assist with no code at all, start here.
If your code or symptom is not covered here, our e-bike repair online guide walks you from a three-minute self-check to the right part.
This guide is part of our e-bike error code lookup and the turns on but won't move fault-finding order. Related Aventon guides: the Aventon throttle guide, when the controller is the real problem and replacing an Aventon display.
Last updated November 4, 2026: added a short answer, a quick-reference table with a source for each code and answers to common questions. Updated again the same day: E21, E27 and E41, E42, E44 in the text above now follow our error-code lookup, and the two published lists for E41, E42 and E44 are shown as they stand, because they disagree. The other code meanings are unchanged.