This article explains how to troubleshoot the E140 Battery Lock Failure error on Aventon eBikes fitted with an ACU/ECU (Aventon Control Unit).

Use this article if your bike:

• Shows an E140 error code
• Does not recognise the battery correctly
• Has battery fitment or locking issues
• Displays a battery lock warning during startup or riding

If you are unsure whether your bike uses an ACU/ECU system, please confirm your Aventon model before continuing.

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

Before You Start

Please prepare the following:

• Order number
• Aventon model
• Photo or video of the E140 error code
• Photo of the battery installed in the frame
• Photo of the battery lock area
• Screenshot of the Aventon App firmware version, if available
• When the issue first appeared
• Whether the bike powers on
• Whether the display turns on
• Whether the battery locks securely into place
• Whether the issue happened after transport, storage, water exposure, crash, impact, modification, firmware update, or third-party repair
• Photos of visible damage

Safety Warnings

• Do not continue riding if the battery is loose or not securely locked into place.
• Do not use the bike if there is visible battery, frame, or lock damage.
• 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 E140 Battery Lock Failure error means the bike cannot confirm that the battery is correctly installed or locked into place.

This may happen if:

• The battery is not fully installed
• The battery lock is damaged
• The ECU software is outdated
• The ECU is damaged

Possible Causes

Possible causes include:

• Battery not installed correctly
• ECU software bug or outdated software
• Damaged battery lock
• Damaged ECU

Troubleshooting Steps

Step 1 – Check That the Battery Is Installed Correctly

To install the battery correctly:

• Press the battery firmly into the frame
• Firmly allow the battery to lock into place
• Confirm the edges of the battery sit flush with the frame

Check whether the battery feels secure and properly seated.

If yes – The battery is installed correctly

Continue to Step 2.

If no – The battery is not installed correctly

Reinstall the battery correctly.

Press the battery firmly into the mounting base and confirm it locks fully into place.

Restart the bike and check whether the E140 error remains.

If the issue clears

The issue was likely caused by the battery not being fully seated or locked correctly.

Monitor the bike during normal use.

If the issue remains

Continue to Step 2.

Step 2 – Update the ECU Software

Using the Aventon App:

• Check for ECU software updates
• Update the ECU software to the latest version

Allow the update process to complete fully.

Restart the bike after updating.

If yes – The E140 error still appears

Continue to Step 3.

If no – The error clears

The issue was likely caused by outdated ECU software.

Continue monitoring the bike during normal use.

If the issue clears

Continue normal use and monitor the bike.

If the issue remains

Continue to Step 3.

Step 3 – Inspect the Battery Lock Area

Inspect the battery lock area for:

• Visible damage
• Loose fitment
• Signs the battery does not fully latch
• Damage around the mounting area
• Water exposure
• Impact damage

If yes – Visible damage is found

Stop using the bike immediately.

Please contact our support team with photos/videos of the battery lock area.

If no – No visible damage is found

Restart the bike and check whether the E140 error returns.

If the issue remains

Continue to Step 4.

Step 4 – Check Whether the Error Persists

After reinstalling the battery and updating the ECU software, check whether:

• The battery locks securely
• The bike powers on normally
• The display operates normally
• The E140 error returns

If yes – The E140 error still appears

The issue may involve:

• The battery lock system
• ECU communication
• ECU operation

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 improper battery installation or outdated ECU software.

Continue monitoring the bike during use.

Step 5 – Check for Battery Movement

With the bike powered off, check whether the battery:

• Moves excessively in the frame
• Feels loose after locking
• Does not sit flush with the frame

If yes

Do not continue riding the bike.

Please contact support with photos/videos of the battery fitment and lock area.

If no

Restart the bike and monitor whether the E140 error returns.

If the issue remains

Please contact support.

When To Contact Support

Please contact support if:

• The E140 error remains after completing these checks
• The battery does not lock securely
• The battery does not sit flush with the frame
• There is visible battery lock damage
• The bike does not power on correctly
• Firmware updates fail repeatedly
• The bike has been exposed to water, crash, impact, transport damage, modification, firmware issues, 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 E140 error code
• Photo of the battery installed in the frame
• Photo/video of the battery lock area
• Screenshot of the Aventon App firmware version
• Photos of visible damage
• Confirmation of whether the bike powers on
• Confirmation of whether the display turns on
• Confirmation of whether the battery locks securely
• Confirmation of whether the battery sits flush with the frame
• Confirmation of whether firmware updates complete successfully
• Confirmation of whether the issue happened after water exposure, crash, impact, modification, firmware update, or third-party repair
• Confirmation of the troubleshooting steps already completed

Important Safety Notes

• Do not continue riding if the battery is loose or the E140 error remains.
• Do not use the bike if there is visible damage, overheating, smoke, or a burning smell.
• Do not open the ECU, battery, controller, or sealed electrical components.
• Do not force the battery into the frame.
• Do not work on wiring while the bike is powered on or connected to the charger.
• Contact support if you are unsure.