Aventon Mid-Drive Bikes – E33 ECU Communication Error TroubleshootingUpdated 2 days ago
This article explains how to troubleshoot the E33 “ECU Communication Error” on Aventon mid-drive bikes.
Use this article if your bike:
- Shows error code E33
- Displays “ECU Communication Error”
- Has intermittent display communication issues
- Experiences communication interruptions between the ECU and display
- Does not properly communicate between the ECU and display harness
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 E33 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
E33 indicates a communication issue between the ECU and display.
The issue may be caused by:
- poor communication signal output
- damaged wiring or connectors
- internal open circuits
- damaged ECU or display harness components
Possible Causes
- no communication signal output from the ECU to the display
- poor connection between the ECU and display
- bug in the current ECU software version
- damaged cable between the ECU and display
- worn cable
- broken connector
- internal open circuit
Troubleshooting Steps
Step 1 – Disconnect, Inspect, and Reconnect the ECU and Display Harness
Disconnect, inspect, clean, and fully reconnect:
- ECU
- display harness
Update the firmware to the latest version using the Aventon app.
After reconnecting and updating the firmware, restart the bike and check whether the E33 code remains.
If the issue clears
The issue was likely caused by a loose connection or outdated firmware.
If the issue remains
Inspect the ECU and display harness for visible damage.
Step 2 – Inspect for Visible Damage
Inspect the following components for visible damage:
- ECU
- display harness
- display
If the display harness is damaged
Replace the display harness.
After replacement, restart the bike and check whether the E33 code remains.
If the display is damaged
Replace the display.
After replacement, restart the bike and check whether the E33 code remains.
If the issue clears
The issue was likely caused by the damaged component that was replaced.
If the issue remains
Replace the remaining display communication component.
Step 3 – Replace the Display or Display Harness
If the display harness was replaced first and the issue remains:
- replace the display
If the display was replaced first and the issue remains:
- replace the display harness
After replacement, restart the bike and check whether the E33 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
Update the ECU software to the latest version using the Aventon app.
Step 4 – Update the ECU Software
Update the ECU software to the latest version using the Aventon app.
After the update completes, restart the bike and check whether the E33 code remains.
If the issue clears
The issue was likely caused by an ECU software bug.
If the issue remains
Replace the ECU following the ECU replacement procedure.
Step 5 – Replace the ECU
If the E33 code still remains after completing the previous steps, the ECU may be faulty.
Replace the ECU following the ECU replacement procedure.
If the issue clears
The issue was likely caused by a faulty ECU.
If the issue remains
Please contact support for further diagnosis.
When To Contact Support
Please contact support if:
- the E33 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 ECU, display harness, connectors, 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 E33 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 E33 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, ECU, display, 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.