Added sources and updated by the Pedalwise team

Yamaha drive units show a two digit error code when the system finds a fault. This list comes from Yamaha's owner's manual for the Booster Easy, which uses a PWseries S2 drive unit with the Yamaha Multifunction LCD display (Booster Easy manual). Other Yamaha displays show errors in their own way, so check your bike's manual too. Most fixes in Yamaha's table are part replacements for a dealer. For the basics, start with Yamaha e-bike troubleshooting.

When an error shows

1. On this display, the riding screen alternates with "Er" and a description of the fault.
2. Turn the power off, then on again.
3. If it stays, Yamaha says to have a dealer inspect the bike as soon as possible (Booster Easy manual).

Yamaha's table also says whether each code clears after a restart. Codes that return after you restart, or never clear, need a dealer.

Display and communication

• 12: communication with the display stopped. Check the display connector is pushed home. If it stays, dealer.
• 13: data between the drive unit and display failed. Yamaha says to confirm the two are compatible, so ask your dealer, especially if a part was changed.

Torque and crank sensors

• 31 and 32: no signal or an intermittent wiring fault at the torque sensor. Dealer.
• 33: abnormal torque sensor voltage at rest. Restart, then dealer if it returns.
• 34 to 37: abnormal torque sensor voltage while riding or at low speed. Dealer if it returns.
• 38 and 39: abnormal crank sensor voltage while the motor is off. Dealer.

See pedal assist sensor and no pedal assist.

Motor and controller

• 61: overcurrent on a motor phase. Dealer.
• 62: overcurrent or abnormal current on the motor phases. Yamaha's table says this one does not clear after a restart. Dealer.
• 63: controller data reading failure. Dealer.
• 64: controller board too cold or too hot, or its sensor loose. Let the bike reach a normal temperature and restart, then dealer if it returns.
• 66: controller memory data error. Dealer.
• 67: a motor lead wire is disconnected. Dealer.
• 68: encoder wire disconnected or shorted. Dealer.
• 79: abnormal current at the DC/DC converter. Dealer.

Battery

• 71: battery data not received correctly. Remove the battery, check it seats and locks, refit and restart. Dealer if it returns.
• 73: battery voltage too high. Dealer.
• 74: internal battery system failure. The charge display may flash oddly. Dealer.

Speed sensor

• Speed sensor disconnected: Yamaha lists this without a number. Check the sensor plug and the gap between sensor and magnet. See align speed sensor magnet.

Other signs on the display

From the same manual (Booster Easy manual):

• Automatic Support indicator flashing: a possible drive unit fault. Restart the display, then dealer.
• Speed missing and the function display flashing: the speed sensor isn't reading. Restart, pick an assist mode, ride a short way, and check the magnet.
• Speed showing and the function display flashing: assist has paused while the system checks itself. This is normal and clears on its own.
• All four battery lights flashing together while charging: the battery is too hot or too cold, and charging resumes once it is back in range.

When to see a dealer

• Any code that returns after a restart, and code 62 straight away.
• Any noise, smoke or unusual smell from the drive unit.
• Any battery code that stays.

More help: Yamaha motors explained, e-bike error codes and when to call a pro.

Videos

Sources

• Booster Easy manual, cdn2.yamaha-motor.eu
• Yamaha LED Electric Bike Display Settings, youtube.com
• How To: Use Yamaha Display, youtube.com

Stuck after these checks? Find a shop near you, or if you're in Austin, book a Pedalwise tech.