Aventon Mid-Drive Bikes – W03 Controller Overheat Protection TroubleshootingUpdated a day ago

This article explains how to troubleshoot the W03 “Controller Overheat Protection” warning on Aventon mid-drive bikes.

Use this article if your bike:

• Shows warning code W03
• Displays “Controller Overheat Protection”
• Temporarily loses motor assistance
• Reduces power output during riding
• Shuts down motor assistance after heavy use

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 W03 warning code
• when the issue first appeared
• whether the bike powers on
• whether the battery charges
• whether the display turns on
• whether the motor engages
• riding conditions before the warning appeared
• whether the issue happened after steep climbing, prolonged heavy riding, hot weather, transport, storage, water exposure, crash, impact, modification, or third-party repair
• photos of any visible damage

Safety Warnings

• Do not continue riding if the controller overheats repeatedly.
• Stop riding immediately if there is smoke, burning smell, excessive heat, or visible electrical damage.
• Allow the bike to cool completely before troubleshooting.
• Do not open sealed electrical components.
• Stop and contact support if you are unsure.

What This Warning Means

W03 indicates the controller entered overheat protection mode.

The system automatically limits or shuts off motor power to prevent damage when excessive controller temperature is detected.

Possible Causes

• prolonged heavy riding
• steep climbing using maximum pedal assist
• excessive controller heat buildup
• damaged mid-drive/controller unit

Troubleshooting Steps

Step 1 – Power Off and Cool Down the Bike

Turn off the e-bike completely.

Allow the bike to cool for at least 1 hour.

After cooling:

1. Power the bike back on
2. Restart the system
3. Check whether the W03 warning remains

If the issue clears

The warning was likely caused by temporary overheating from sustained heavy motor use.

To help prevent future overheating:

• reduce pedal assist level on steep climbs
• avoid prolonged maximum power operation
• allow cooling breaks during long or demanding rides
• avoid extended riding in extreme heat

If the issue remains

Proceed with controller replacement.

Step 2 – Replace the Mid-Drive Unit

Replace the mid-drive unit if:

• the W03 warning remains after cooling and restarting
• overheating occurs repeatedly during normal riding
• the bike frequently loses motor assistance
• the warning appears shortly after startup
• there are signs of internal controller failure

After replacement:

1. Restart the bike
2. Test motor operation
3. Confirm the W03 warning no longer appears

If the issue clears

The issue was likely caused by a damaged or overheating controller within the mid-drive unit.

If the issue remains

Please contact support for additional diagnosis.

When To Contact Support

Please contact support if:

• the W03 warning remains after completing the steps above
• the bike overheats repeatedly
• the motor shuts down unexpectedly
• there is smoke, burning smell, or excessive heat
• the motor does not engage
• the display does not power on
• the issue appeared after water exposure, crash, impact, 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 W03 warning code
• photo of the display
• photo or video showing the issue
• description of riding conditions before the warning appeared
• 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 overheating happens repeatedly
• 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 overheating occurs repeatedly.
• Stop using the bike immediately if there is visible damage, smoke, burning smell, or excessive heat.
• Allow the system to cool completely before troubleshooting.
• Do not open the battery, controller, display, or mid-drive unit.
• Contact support if you are unsure.