This article explains how to troubleshoot the E25 Brake Sensor Error on an Aventon eBike.

Use this article if your bike:

• Shows an E25 error code
• Has reduced or no motor assistance
• Displays a brake-related warning
• Acts as though the brakes are constantly engaged

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

Stop troubleshooting immediately if anything looks unsafe, damaged, or if the brakes are not operating normally.

Before You Start

Please prepare the following:

• Order number
• Aventon model
• Photo or video of the E25 error code
• Photo of the display
• Photo of both brake levers
• Photo of accessible brake sensor connectors, if relevant
• When the issue first appeared
• Whether the bike powers on
• Whether the display turns on
• Whether the motor engages
• Whether the issue happened after transport, storage, water exposure, crash, impact, modification, or third-party repair
• Photos of visible damage

Safety Warnings

• Do not continue riding if the brakes are not operating normally.
• Do not continue riding if the bike has visible damage, overheating, smoke, or exposed wiring.
• 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 E25 error means the bike has detected a brake sensor issue.

This may happen if:

• A brake lever was held down when the bike was turned on
• A brake lever shutoff sensor needs adjustment
• A brake sensor, wire harness, or controller issue is present

Some Tektro brake systems have adjustable sensors.

Possible Causes

Possible causes include:

• Brake lever held during startup
• Brake sensor adjustment issue
• Damaged brake sensor
• Damaged wire harness
• Damaged controller
• Loose brake sensor connection
• Visible cable or connector damage

Troubleshooting Steps

Step 1 – Reset the Brake Levers

Turn the bike off before continuing.

Press and release both brake levers several times.

Make sure both levers return normally and are not sticking.

Restart the bike without touching either brake lever.

If yes – The E25 code still appears

Continue to Step 2.

If no – The error clears

The issue was likely caused by the brake lever being engaged during startup.

Monitor the bike during normal use.

If the issue remains

Continue to Step 2.

Step 2 – Disconnect Both Brake Sensor Connections

Turn the bike off before continuing.

Disconnect both the left and right brake sensor connections if they are safely accessible.

Restart the bike and check whether the E25 error remains.

If yes – The code still appears

The issue may involve the wire harness 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 clears

Continue to Step 3.

If the issue remains

Please contact support.

Step 3 – Test the Right Brake Lever Sensor

Turn the bike off before continuing.

Reconnect only the right-side brake lever sensor.

Restart the bike and check whether the E25 error returns.

If yes – The E25 code returns

The right brake lever or sensor may require adjustment or replacement.

Please contact our support team with photos of the right brake lever and connector area.

If no – The E25 code does not return

Continue to Step 4.

If the issue clears

The issue may have been caused by a temporary connection issue.

Monitor the bike during use.

If the issue remains

Continue to Step 4.

Step 4 – Test the Left Brake Lever Sensor

Turn the bike off before continuing.

Disconnect the right-side brake lever sensor.

Connect only the left-side brake lever sensor.

Restart the bike and check whether the E25 error returns.

If yes – The E25 code returns

The left brake lever or sensor may require adjustment or replacement.

Please contact our support team with photos of the left brake lever and connector area.

If no – The E25 code does not return

The right brake lever or sensor may require adjustment or replacement.

Please contact support with photos of the right brake lever and connector area.

If the issue remains

Please contact support.

When To Contact Support

Please contact support if:

• The E25 error remains after completing these checks
• The brake levers do not return normally
• The motor does not engage
• 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 E25 error code
• Photo of the display
• Photo of both brake levers
• Photo of accessible brake sensor connectors, if safe
• Photos of visible damage
• Confirmation of whether the bike powers on
• Confirmation of whether the display turns on
• Confirmation of whether the motor engages
• Confirmation of whether the issue started after 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 E25 error remains.
• Do not ride the bike if the brakes are not functioning normally.
• Do not open the 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.