This article explains how to troubleshoot the E31 (C.A.N.) Battery Communication Failure error on an Aventon eBike.

Use this article if your bike:

• Shows an E31 error code
• Has battery communication issues
• Powers on intermittently
• The display cannot communicate with the battery system
• Motor assistance does not operate normally

If you are unsure of your Aventon model, please confirm your model before continuing.

Stop troubleshooting immediately if anything looks unsafe, damaged, overheated, swollen, or smells burnt.

Before You Start

Please prepare the following:

• Order number
• Aventon model
• Photo or video of the E31 error code
• Photo of the display
• Photo of the battery area
• Photo of accessible display and battery connectors
• 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, transport, storage, water exposure, crash, impact, modification, or third-party repair
• Photos of visible damage

Safety Warnings

• Do not continue riding if the bike has visible damage, overheating, smoke, or a burning smell.
• Do not continue using the bike if the battery appears swollen or damaged.
• 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

The E31 (C.A.N.) Battery Communication Failure error means the battery is not communicating correctly with the display.

This may happen if:

• There is a poor connection between the battery and display
• The battery harness is damaged
• The display harness is damaged
• The battery or display is damaged
• There is cable or connector damage

Possible Causes

Possible causes include:

• Poor battery-to-display connection
• Damaged battery
• Damaged display
• Damaged display harness
• Worn cable
• Broken connector
• Internal open circuit
• Damaged terminal
• Visible cable or connector damage

Troubleshooting Steps

Step 1 – Inspect and Reconnect the Battery and Display Harness

Turn the bike off before continuing.

Disconnect, inspect, clean, and reconnect the accessible:

• Battery connection
• Display connection
• Display harness
• Battery harness

Check for:

• Loose connections
• Bent pins
• Worn cables
• Broken connectors
• Dirt or contamination
• Visible cable damage

Update the bike firmware to the latest version using the Aventon App if available.

Restart the bike and check whether the E31 error remains.

If yes – Visible damage is found

Continue to the relevant section below:

• Display damage
• Battery damage
• Display harness damage

If no – No visible damage is found

Restart the bike after reconnecting all accessible connections.

Check whether the E31 error remains.

If the issue clears

The issue was likely caused by a loose connection or temporary communication issue.

Monitor the bike during normal use.

If the issue remains

Continue to Step 2.

Step 2 – Check Whether the Error Persists After Reconnecting

After reconnecting all accessible connections and restarting the bike, check whether the E31 error returns.

If yes – The E31 code still appears

The issue may involve the display, battery, display harness, terminal, or controller system.

Please contact our support team with the photos/videos listed below so we can review the next step.

If no – The error no longer appears

The issue was likely caused by a temporary communication or connection issue.

Continue monitoring the bike during use.

Visible Damage Troubleshooting

Step 3 – Display Damage Found

Inspect the display for:

• Cracked screen
• Physical damage
• Water exposure
• Loose wiring
• Broken mounting points

If yes

Do not continue riding the bike.

Please contact our support team with photos of the display and error code.

If the issue remains

The display harness, battery system, or controller system may also be affected.

Please contact support.

Step 4 – Battery Damage Found

Inspect the battery for:

• Cracks
• Swelling
• Water exposure
• Burning smell
• Overheating
• Damaged terminals

If yes

Stop using the bike and battery immediately.

Do not continue charging or riding the bike.

Please contact our support team with photos/videos of the battery and charger.

If the issue remains

The display harness or controller system may also require further inspection.

Please contact support.

Step 5 – Display Harness Damage Found

Inspect the accessible display harness and terminal area for:

• Cuts
• Worn insulation
• Pinched cables
• Loose connectors
• Bent pins
• Broken fittings

If yes

Do not continue riding the bike.

Please contact our support team with photos of the damaged harness and connectors.

If the issue remains

The display, battery, or controller system may also require further inspection.

Please contact support.

Step 6 – Check Whether Communication Problems Continue

Check whether:

• The display powers on intermittently
• The bike loses communication with the battery
• The E31 error returns repeatedly
• The bike does not operate normally

If yes

The issue may involve:

• The battery communication system
• Display communication
• The display harness
• The controller system

Please contact our support team with:

• Video of the issue
• Video of the display during startup
• Photos of accessible connectors and wiring

If the issue remains

Please contact support.

When To Contact Support

Please contact support if:

• The E31 error remains after completing these checks
• The bike does not power on
• The battery does not charge
• The display does not turn on
• There is visible cable or connector damage
• 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

If the issue remains after these steps, please contact our support team and include the photos/videos listed below.

What To Send Support

Please send:

• Order number
• Aventon model
• Photo/video of the E31 error code
• Photo of the display
• Photo of the battery area
• Photo of accessible display and battery connectors, 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 the issue happened after charging, transport, water exposure, crash, impact, modification, or third-party repair
• Confirmation of the troubleshooting steps already completed

Important Safety Notes

• Do not continue riding if the E31 error remains.
• Do not ride the bike if there is visible damage, overheating, smoke, burning smell, or battery swelling.
• Do not open the battery, controller, 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.