Aventon Mid-Drive Bikes – E31 Battery Communication Error TroubleshootingUpdated 2 days ago
This article explains how to troubleshoot the E31 “Battery Communication Error” on Aventon mid-drive bikes.
Use this article if your bike:
- Shows error code E31
- Displays “Battery Communication Error”
- Has intermittent battery communication issues
- Experiences display or power interruptions
- Does not properly communicate between the battery, display, and mid-drive unit
If you are unsure about any step or notice anything unsafe, stop troubleshooting and contact support.
Before You Start
Please prepare the following:
- order number
- Aventon model
- photo or video of the issue
- photo of the E31 error code
- when the issue first appeared
- whether the bike powers on
- whether the battery charges
- whether the display turns on
- whether the motor engages
- whether the issue happened after charging, riding, transport, storage, water exposure, crash, impact, modification, or third-party repair
- photos of any visible damage
Safety Warnings
- Do not continue riding if the bike has visible damage, overheating, smoke, burning smell, water exposure, or a persistent error code.
- Do not open sealed electrical components.
- Do not work on wiring while the bike is powered on or charging.
- Stop and contact support if you are unsure.
What This Error Means
E31 indicates a communication issue between the battery, display, and mid-drive unit.
The issue may be caused by:
- poor communication signal output
- damaged wiring or connectors
- internal open circuits
- damaged display, harness, battery, or mid-drive components
Possible Causes
- no communication signal output from the battery to the display
- poor connection between the battery and display
- damaged cable between the battery and display
- worn cable
- broken connector
- internal open circuit
Troubleshooting Steps
Step 1 – Inspect the Display, Harness, Mid-Drive Unit, and Battery
Inspect the following components for visible damage:
- display
- display harness
- mid-drive unit
- battery
If yes
Identify which component is damaged:
- display
- display harness
- battery
Replace the damaged component.
If no
Clean all electrical connections and reconnect the display and harness connections.
After reconnecting, restart the bike and check whether the E31 code remains.
If the issue clears
The issue was likely caused by a loose or dirty connection.
If the issue remains
Replace the display and display harness.
Step 2 – Replace the Display
If the display is visibly damaged, replace the display.
After replacement, restart the bike and check whether the E31 code remains.
If the issue clears
The issue was likely caused by a faulty display.
If the issue remains
Replace the display harness.
Step 3 – Replace the Display Harness
If the display harness is visibly damaged, replace the display harness.
After replacement, restart the bike and check whether the E31 code remains.
If the issue clears
The issue was likely caused by a faulty display harness.
If the issue remains
Replace the display.
Step 4 – Replace the Battery
If the battery is visibly damaged, replace the battery.
You should also replace the battery if:
- the issue remains after replacing the display
- the issue remains after replacing the display harness
After replacement, restart the bike and check whether the E31 code remains.
If the issue clears
The issue was likely caused by a faulty battery.
If the issue remains
Replace the display and display harness.
Step 5 – Replace the Display and Display Harness
Replace both:
- the display
- the display harness
After replacement, restart the bike and check whether the E31 code remains.
If the issue clears
The issue was likely caused by a communication failure between the display and harness system.
If the issue remains
Replace the mid-drive unit.
Step 6 – Replace the Mid-Drive Unit
Replace the mid-drive unit if:
- the issue remains after replacing the battery
- the issue remains after replacing the display and display harness
- communication issues continue after all previous troubleshooting steps
After replacement, restart the bike and check whether the E31 code remains.
If the issue clears
The issue was likely caused by a faulty mid-drive unit.
If the issue remains
Please contact support for further diagnosis.
When To Contact Support
Please contact support if:
- the E31 error remains after completing the steps above
- there is visible damage
- the battery does not charge
- the bike does not power on
- the display does not power on
- the motor does not engage
- the issue appears related to the battery, display, harness, connectors, mid-drive unit, or internal wiring
- the bike has been exposed to water, crash, impact, transport damage, modification, or third-party repair
- you are unsure how to safely complete a step
- you need warranty, repair, replacement part, refund, or replacement support
If the issue remains after this step, please contact our support team and include the photos/videos listed below.
What To Send Support
Please send:
- order number
- Aventon model
- photo or video of the E31 error code
- photo of the display
- photo of the battery area
- photo of accessible connectors or harnesses, if safe
- photos of visible damage
- confirmation of whether the bike powers on
- confirmation of whether the battery charges
- confirmation of whether the display turns on
- confirmation of whether the motor engages
- confirmation of whether there was water exposure, crash, impact, modification, or third-party repair
- list of troubleshooting steps already completed
Important Safety Notes
- Do not continue riding if the E31 error remains.
- Do not ride if there is visible damage, overheating, smoke, burning smell, water exposure, or motor resistance.
- Do not open the battery, controller, display, mid-drive unit, or sealed electrical components.
- Do not force connectors.
- Do not work on wiring while the bike is powered on or connected to the charger.
- Contact support if you are unsure.