Communication failed

Stop riding Last verified: pending review Reviewed by: editorial team

Quick answer

Error code 30 signifies a communication failure between the display and the controller in Bafang systems. This error prevents the motor from functioning, although other bike systems may still operate normally. It is a common issue that usually stems from connection problems rather than a fault in the motor itself.

Stop riding Wiring & communication Often DIY-friendly Beginner (15–30 min)

Does this apply to your bike?

H700 · Bafang · Common displays: DP E171

Heads-up: the same number can mean different things on other systems — always check your drive system first. Browse all drive systems →

What you’ll notice

The display shows error code 30, and the motor does not respond to pedaling or throttle input.

Likely causes, ranked

Start at #1 — causes are ordered by how often they turn out to be the problem.

#1 Loose or Corroded Connectors

How to check: Inspect all connectors for tightness and corrosion.

#2 Damaged Wiring Harness

How to check: Check for pinched or damaged wires, especially near the controller.

#3 Faulty Display

How to check: Test with a different display to see if the error persists.

#4 Moisture in Connectors

How to check: Look for signs of moisture or silicone interference in connectors.

#5 Controller Issues

How to check: If other checks fail, consider testing or replacing the controller.

#6 Sensor Cable Damage

How to check: Inspect speed and gear sensor cables for damage.

Troubleshooting steps

Check All Connections

easy

Inspect all connectors for tightness and corrosion.

If it passes →Check Wiring Harness

If it fails →Repair or replace damaged connectors.
Check Wiring Harness

easy

Look for pinched or damaged wires, especially near the controller.

If it passes →Test Display

If it fails →Repair or replace damaged wiring.
Test the Display

easy

Swap the display with a known working one to rule out display issues.

If it passes →Check for Error 30

If it fails →Replace the display.
Inspect for Moisture

easy

Check connectors for moisture or silicone interference.

If it passes →Check for Error 30

If it fails →Clean or replace affected connectors.
Check Controller

intermediate

If the error persists, consider testing or replacing the controller.

If it passes →Check for Error 30

If it fails →Replace the controller.
Inspect Sensor Cables

easy

Check speed and gear sensor cables for any visible damage.

If it passes →Check for Error 30

If it fails →Repair or replace damaged sensor cables.

When to stop and get professional help

If the motor does not respond after checking all components, consult a professional.

Never open, puncture, or disassemble the battery pack, and never bypass the BMS. See our safety guide.

More codes for H700

25 · Torque signal fault 26 · Torque sensor speed signal fault 27 · Over current of the controller 33 · Brake detection circuit is fault 35 · Detection circuit for 15V has an error 36 · Detection circuit on the keypad has an error

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Sources & verification

Last verified: pending review Reviewed by: editorial team

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